diff --git a/question/type/calculated/questiontype.php b/question/type/calculated/questiontype.php
index 988a17960069e..7bd48f6112019 100644
--- a/question/type/calculated/questiontype.php
+++ b/question/type/calculated/questiontype.php
@@ -39,17 +39,17 @@
  */
 class qtype_calculated extends question_type {
     /**
-     * @const string a placeholder is a letter, followed by almost any characters. (This should probably be restricted more.)
+     * @var string a placeholder is a letter, followed by almost any characters. (This should probably be restricted more.)
      */
     const PLACEHOLDER_REGEX_PART = '[[:alpha:]][^>} <`{"\']*';
 
     /**
-     * @const string REGEXP for a placeholder, wrapped in its {...} delimiters, with capturing brackets around the name.
+     * @var string REGEXP for a placeholder, wrapped in its {...} delimiters, with capturing brackets around the name.
      */
     const PLACEHODLER_REGEX = '~\{(' . self::PLACEHOLDER_REGEX_PART . ')\}~';
 
     /**
-     * @const string Regular expression that finds the formulas in content, with capturing brackets to get the forumlas.
+     * @var string Regular expression that finds the formulas in content, with capturing brackets to get the forumlas.
      */
     const FORMULAS_IN_TEXT_REGEX = '~\{=([^{}]*(?:\{' . self::PLACEHOLDER_REGEX_PART . '\}[^{}]*)*)\}~';
 
@@ -63,7 +63,7 @@ public function get_question_options($question) {
         global $CFG, $DB, $OUTPUT;
         parent::get_question_options($question);
         if (!$question->options = $DB->get_record('question_calculated_options',
-                array('question' => $question->id))) {
+                ['question' => $question->id])) {
             $question->options = new stdClass();
             $question->options->synchronize = 0;
             $question->options->single = 0;
@@ -83,7 +83,7 @@ public function get_question_options($question) {
                  {question_calculated} c
             WHERE a.question = ?
             AND   a.id = c.answer
-            ORDER BY a.id ASC", array($question->id))) {
+            ORDER BY a.id ASC", [$question->id])) {
                 return false;
         }
 
@@ -93,7 +93,7 @@ public function get_question_options($question) {
         }
 
         $question->hints = $DB->get_records('question_hints',
-                array('questionid' => $question->id), 'id ASC');
+                ['questionid' => $question->id], 'id ASC');
 
         if (isset($question->export_process)&&$question->export_process) {
             $question->options->datasets = $this->get_datasets_for_export($question);
@@ -103,12 +103,12 @@ public function get_question_options($question) {
 
     public function get_datasets_for_export($question) {
         global $DB, $CFG;
-        $datasetdefs = array();
+        $datasetdefs = [];
         if (!empty($question->id)) {
             $sql = "SELECT i.*
                       FROM {question_datasets} d, {question_dataset_definitions} i
                      WHERE d.question = ? AND d.datasetdefinition = i.id";
-            if ($records = $DB->get_records_sql($sql, array($question->id))) {
+            if ($records = $DB->get_records_sql($sql, [$question->id])) {
                 foreach ($records as $r) {
                     $def = $r;
                     if ($def->category == '0') {
@@ -124,7 +124,7 @@ public function get_datasets_for_export($question) {
                     $def->decimals = $dec;
                     if ($def->itemcount > 0) {
                         // Get the datasetitems.
-                        $def->items = array();
+                        $def->items = [];
                         if ($items = $this->get_database_dataset_items($def->id)) {
                             $n = 0;
                             foreach ($items as $ii) {
@@ -155,7 +155,7 @@ public function save_question_options($question) {
         // Calculated options.
         $update = true;
         $options = $DB->get_record('question_calculated_options',
-                array('question' => $question->id));
+                ['question' => $question->id]);
         if (!$options) {
             $update = false;
             $options = new stdClass();
@@ -168,11 +168,11 @@ public function save_question_options($question) {
             $options->synchronize = 0;
         }
         $options->single = 0;
-        $options->answernumbering =  $question->answernumbering;
+        $options->answernumbering = $question->answernumbering;
         $options->shuffleanswers = $question->shuffleanswers;
 
-        foreach (array('correctfeedback', 'partiallycorrectfeedback',
-                'incorrectfeedback') as $feedbackname) {
+        foreach (['correctfeedback', 'partiallycorrectfeedback',
+                'incorrectfeedback'] as $feedbackname) {
             $options->$feedbackname = '';
             $feedbackformat = $feedbackname . 'format';
             $options->$feedbackformat = 0;
@@ -186,10 +186,10 @@ public function save_question_options($question) {
 
         // Get old versions of the objects.
         $oldanswers = $DB->get_records('question_answers',
-                array('question' => $question->id), 'id ASC');
+                ['question' => $question->id], 'id ASC');
 
         $oldoptions = $DB->get_records('question_calculated',
-                array('question' => $question->id), 'answer ASC');
+                ['question' => $question->id], 'answer ASC');
 
         // Save the units.
         $virtualqtype = $this->get_virtual_qtype();
@@ -248,14 +248,14 @@ public function save_question_options($question) {
         // Delete old answer records.
         if (!empty($oldanswers)) {
             foreach ($oldanswers as $oa) {
-                $DB->delete_records('question_answers', array('id' => $oa->id));
+                $DB->delete_records('question_answers', ['id' => $oa->id]);
             }
         }
 
         // Delete old answer records.
         if (!empty($oldoptions)) {
             foreach ($oldoptions as $oo) {
-                $DB->delete_records('question_calculated', array('id' => $oo->id));
+                $DB->delete_records('question_calculated', ['id' => $oo->id]);
             }
         }
 
@@ -284,7 +284,7 @@ public function import_datasets($question) {
             $datasetdef = new stdClass();
             $datasetdef->name = $dataset->name;
             $datasetdef->type = 1;
-            $datasetdef->options =  $dataset->distribution . ':' . $dataset->min . ':' .
+            $datasetdef->options = $dataset->distribution . ':' . $dataset->min . ':' .
                     $dataset->max . ':' . $dataset->length;
             $datasetdef->itemcount = $dataset->itemcount;
             if ($dataset->status == 'private') {
@@ -296,10 +296,10 @@ public function import_datasets($question) {
                     "type = '1'
                     AND " . $DB->sql_equal('name', '?') . "
                     AND category = ?
-                    ORDER BY id DESC ", array($dataset->name, $question->category)
+                    ORDER BY id DESC ", [$dataset->name, $question->category]
                 )) { // So there is at least one.
                     $sharedatasetdef = array_shift($sharedatasetdefs);
-                    if ($sharedatasetdef->options ==  $datasetdef->options) {// Identical so use it.
+                    if ($sharedatasetdef->options == $datasetdef->options) {// Identical so use it.
                         $todo = 'useit';
                         $datasetdef = $sharedatasetdef;
                     } else { // Different so create a private one.
@@ -339,7 +339,7 @@ public function import_datasets($question) {
      * @param stdClass $questiondata The question data object.
      */
     protected function initialise_calculated_answers(question_definition $question, stdClass $questiondata) {
-        $question->answers = array();
+        $question->answers = [];
         if (empty($questiondata->options->answers)) {
             return;
         }
@@ -541,7 +541,7 @@ public function preparedatasets($form, $questionfromid = '0') {
         // The dataset names present in the edit_question_form and edit_calculated_form
         // are retrieved.
         $possibledatasets = $this->find_dataset_names($form->questiontext);
-        $mandatorydatasets = array();
+        $mandatorydatasets = [];
         foreach ($form->answer as $key => $answer) {
             $mandatorydatasets += $this->find_dataset_names($answer);
         }
@@ -551,7 +551,7 @@ public function preparedatasets($form, $questionfromid = '0') {
         if ($questionfromid != '0') {
             $form->id = $questionfromid;
         }
-        $datasets = array();
+        $datasets = [];
         $key = 0;
         // Always prepare the mandatorydatasets present in the answers.
         // The $options are not used here.
@@ -590,7 +590,7 @@ public function addnamecategory(&$question) {
                 AND a.type = '1'
                 AND a.category != 0
                 AND b.question = ?
-           ORDER BY a.name ", array($question->id));
+           ORDER BY a.name ", [$question->id]);
         $questionname = $this->clean_technical_prefix_from_question_name($question->name);
 
         if (!empty($categorydatasetdefs)) {
@@ -603,7 +603,7 @@ public function addnamecategory(&$question) {
             }
             $questionname = '#' . $questionname;
         }
-        $DB->set_field('question', 'name', $questionname, array('id' => $question->id));
+        $DB->set_field('question', 'name', $questionname, ['id' => $question->id]);
     }
 
     /**
@@ -633,7 +633,7 @@ public function save_question($question, $form) {
             return $question;
         }
 
-        $wizardnow =  optional_param('wizardnow', '', PARAM_ALPHA);
+        $wizardnow = optional_param('wizardnow', '', PARAM_ALPHA);
         $id = optional_param('id', 0, PARAM_INT); // Question id.
         // In case 'question':
         // For a new question $form->id is empty
@@ -647,7 +647,7 @@ public function save_question($question, $form) {
         switch($wizardnow) {
             case '' :
             case 'question': // Coming from the first page, creating the second.
-                if (empty($form->id)) { // or a new question $form->id is empty.
+                if (empty($form->id)) { // Or a new question $form->id is empty.
                     $question = parent::save_question($question, $form);
                     // Prepare the datasets using default $questionfromid.
                     $this->preparedatasets($form);
@@ -657,7 +657,7 @@ public function save_question($question, $form) {
                         $this->addnamecategory($question);
                     }
                 } else {
-                    $questionfromid =  $form->id;
+                    $questionfromid = $form->id;
                     $question = parent::save_question($question, $form);
                     // Prepare the datasets.
                     $this->preparedatasets($form, $questionfromid);
@@ -679,7 +679,7 @@ public function save_question($question, $form) {
                     $optionssynchronize = 0;
                 }
                 $DB->set_field('question_calculated_options', 'synchronize', $optionssynchronize,
-                        array('question' => $question->id));
+                        ['question' => $question->id]);
                 if (isset($form->synchronize) && $form->synchronize == 2) {
                     $this->addnamecategory($question);
                 }
@@ -700,22 +700,22 @@ public function save_question($question, $form) {
     public function delete_question($questionid, $contextid) {
         global $DB;
 
-        $DB->delete_records('question_calculated', array('question' => $questionid));
-        $DB->delete_records('question_calculated_options', array('question' => $questionid));
-        $DB->delete_records('question_numerical_units', array('question' => $questionid));
-        if ($datasets = $DB->get_records('question_datasets', array('question' => $questionid))) {
+        $DB->delete_records('question_calculated', ['question' => $questionid]);
+        $DB->delete_records('question_calculated_options', ['question' => $questionid]);
+        $DB->delete_records('question_numerical_units', ['question' => $questionid]);
+        if ($datasets = $DB->get_records('question_datasets', ['question' => $questionid])) {
             foreach ($datasets as $dataset) {
                 if (!$DB->get_records_select('question_datasets',
                         "question != ? AND datasetdefinition = ? ",
-                        array($questionid, $dataset->datasetdefinition))) {
+                        [$questionid, $dataset->datasetdefinition])) {
                     $DB->delete_records('question_dataset_definitions',
-                            array('id' => $dataset->datasetdefinition));
+                            ['id' => $dataset->datasetdefinition]);
                     $DB->delete_records('question_dataset_items',
-                            array('definition' => $dataset->datasetdefinition));
+                            ['definition' => $dataset->datasetdefinition]);
                 }
             }
         }
-        $DB->delete_records('question_datasets', array('question' => $questionid));
+        $DB->delete_records('question_datasets', ['question' => $questionid]);
 
         parent::delete_question($questionid, $contextid);
     }
@@ -736,7 +736,7 @@ public function supports_dataset_item_generation() {
 
     public function custom_generator_tools_part($mform, $idx, $j) {
 
-        $minmaxgrp = array();
+        $minmaxgrp = [];
         $minmaxgrp[] = $mform->createElement('float', "calcmin[{$idx}]",
                 get_string('calcmin', 'qtype_calculated'));
         $minmaxgrp[] = $mform->createElement('float', "calcmax[{$idx}]",
@@ -748,8 +748,8 @@ public function custom_generator_tools_part($mform, $idx, $j) {
         $mform->addElement('select', "calclength[{$idx}]",
                 get_string('calclength', 'qtype_calculated'), $precisionoptions);
 
-        $distriboptions = array('uniform' => get_string('uniform', 'qtype_calculated'),
-                'loguniform' => get_string('loguniform', 'qtype_calculated'));
+        $distriboptions = ['uniform' => get_string('uniform', 'qtype_calculated'),
+                'loguniform' => get_string('loguniform', 'qtype_calculated')];
         $mform->addElement('select', "calcdistribution[{$idx}]",
                 get_string('calcdistribution', 'qtype_calculated'), $distriboptions);
     }
@@ -774,20 +774,20 @@ public function custom_generator_tools($datasetdef) {
         if (preg_match('~^(uniform|loguniform):([^:]*):([^:]*):([0-9]*)$~',
                 $datasetdef->options, $regs)) {
             $defid = "{$datasetdef->type}-{$datasetdef->category}-{$datasetdef->name}";
-            for ($i = 0; $i<10; ++$i) {
+            for ($i = 0; $i < 10; ++$i) {
                 $lengthoptions[$i] = get_string(($regs[1] == 'uniform'
                     ? 'decimals'
                     : 'significantfigures'), 'qtype_calculated', $i);
             }
             $menu1 = html_writer::label(get_string('lengthoption', 'qtype_calculated'),
-                'menucalclength', false, array('class' => 'accesshide'));
-            $menu1 .= html_writer::select($lengthoptions, 'calclength[]', $regs[4], null, array('class' => 'custom-select'));
+                'menucalclength', false, ['class' => 'accesshide']);
+            $menu1 .= html_writer::select($lengthoptions, 'calclength[]', $regs[4], null, ['class' => 'custom-select']);
 
-            $options = array('uniform' => get_string('uniformbit', 'qtype_calculated'),
-                'loguniform' => get_string('loguniformbit', 'qtype_calculated'));
+            $options = ['uniform' => get_string('uniformbit', 'qtype_calculated'),
+                'loguniform' => get_string('loguniformbit', 'qtype_calculated')];
             $menu2 = html_writer::label(get_string('distributionoption', 'qtype_calculated'),
-                'menucalcdistribution', false, array('class' => 'accesshide'));
-            $menu2 .= html_writer::select($options, 'calcdistribution[]', $regs[1], null, array('class' => 'custom-select'));
+                'menucalcdistribution', false, ['class' => 'accesshide']);
+            $menu2 .= html_writer::select($options, 'calcdistribution[]', $regs[1], null, ['class' => 'custom-select']);
             return '<input type="submit" class="btn btn-secondary" onclick="'
                 . "getElementById('addform').regenerateddefid.value='{$defid}'; return true;"
                 .'" value="'. get_string('generatevalue', 'qtype_calculated') . '"/><br/>'
@@ -815,20 +815,20 @@ public function update_dataset_options($datasetdefs, $form) {
             $uniquedefs = array_values(array_unique($form->definition));
             foreach ($uniquedefs as $key => $defid) {
                 if (isset($datasetdefs[$defid])
-                        && is_numeric($form->calcmin[$key+1])
-                        && is_numeric($form->calcmax[$key+1])
-                        && is_numeric($form->calclength[$key+1])) {
-                    switch     ($form->calcdistribution[$key+1]) {
+                        && is_numeric($form->calcmin[$key + 1])
+                        && is_numeric($form->calcmax[$key + 1])
+                        && is_numeric($form->calclength[$key + 1])) {
+                    switch     ($form->calcdistribution[$key + 1]) {
                         case 'uniform': case 'loguniform':
-                            $datasetdefs[$defid]->options =
-                                $form->calcdistribution[$key+1] . ':'
-                                . $form->calcmin[$key+1] . ':'
-                                . $form->calcmax[$key+1] . ':'
-                                . $form->calclength[$key+1];
+                                $datasetdefs[$defid]->options =
+                                $form->calcdistribution[$key + 1] . ':'
+                                . $form->calcmin[$key + 1] . ':'
+                                . $form->calcmax[$key + 1] . ':'
+                                . $form->calclength[$key + 1];
                             break;
                         default:
                             echo $OUTPUT->notification(
-                                    "Unexpected distribution ".$form->calcdistribution[$key+1]);
+                                    "Unexpected distribution ".$form->calcdistribution[$key + 1]);
                     }
                 }
             }
@@ -847,7 +847,7 @@ public function save_question_calculated($question, $fromform) {
         global $DB;
 
         foreach ($question->options->answers as $key => $answer) {
-            if ($options = $DB->get_record('question_calculated', array('answer' => $key))) {
+            if ($options = $DB->get_record('question_calculated', ['answer' => $key])) {
                 $options->tolerance = trim($fromform->tolerance[$key]);
                 $options->tolerancetype  = trim($fromform->tolerancetype[$key]);
                 $options->correctanswerlength  = trim($fromform->correctanswerlength[$key]);
@@ -866,11 +866,11 @@ public function save_question_calculated($question, $fromform) {
      */
     public function get_database_dataset_items($definition) {
         global $CFG, $DB;
-        $databasedataitems = $DB->get_records_sql(// Use number as key!!
+        $databasedataitems = $DB->get_records_sql( // Hint: Use the number as a key.
             " SELECT id , itemnumber, definition,  value
             FROM {question_dataset_items}
-            WHERE definition = $definition order by id DESC ", array($definition));
-        $dataitems = Array();
+            WHERE definition = $definition order by id DESC ", [$definition]);
+        $dataitems = [];
         foreach ($databasedataitems as $id => $dataitem) {
             if (!isset($dataitems[$dataitem->itemnumber])) {
                 $dataitems[$dataitem->itemnumber] = $dataitem;
@@ -896,7 +896,7 @@ public function save_dataset_items($question, $fromform) {
         }
 
         // Get the old datasets for this question.
-        $datasetdefs = $this->get_dataset_definitions($question->id, array());
+        $datasetdefs = $this->get_dataset_definitions($question->id, []);
         // Handle generator options...
         $olddatasetdefs = fullclone($datasetdefs);
         $datasetdefs = $this->update_dataset_options($datasetdefs, $fromform);
@@ -923,7 +923,7 @@ public function save_dataset_items($question, $fromform) {
         foreach ($fromform->definition as $key => $defid) {
             // If the delete button has not been pressed then skip the datasetitems
             // in the 'add item' part of the form.
-            if ($i > count($datasetdefs)*$maxnumber) {
+            if ($i > count($datasetdefs) * $maxnumber) {
                 break;
             }
             $addeditem = new stdClass();
@@ -978,7 +978,7 @@ public function save_dataset_items($question, $fromform) {
                     $datasetdefs[$defid]->items =
                             $this->get_database_dataset_items($datasetdef->id);
                 }
-                for ($numberadded = $maxnumber+1; $numberadded <= $maxnumber + $numbertoadd; $numberadded++) {
+                for ($numberadded = $maxnumber + 1; $numberadded <= $maxnumber + $numbertoadd; $numberadded++) {
                     if (isset($datasetdefs[$defid]->items[$numberadded])) {
                         // In case of regenerate it modifies the already existing record.
                         if ($defregenerate) {
@@ -1017,16 +1017,16 @@ public function save_dataset_items($question, $fromform) {
 
         if (isset($fromform->deletebutton)) {
             if (isset($fromform->selectdelete)) {
-                $newmaxnumber = $maxnumber-$fromform->selectdelete;
+                $newmaxnumber = $maxnumber - $fromform->selectdelete;
             } else {
-                $newmaxnumber = $maxnumber-1;
+                $newmaxnumber = $maxnumber - 1;
             }
             if ($newmaxnumber < 0) {
                 $newmaxnumber = 0;
             }
             foreach ($datasetdefs as $datasetdef) {
                 if ($datasetdef->itemcount == $maxnumber) {
-                    $datasetdef->itemcount= $newmaxnumber;
+                    $datasetdef->itemcount = $newmaxnumber;
                     $DB->update_record('question_dataset_definitions', $datasetdef);
                 }
             }
@@ -1039,12 +1039,12 @@ public function generate_dataset_item($options) {
             return false;
         }
         if ($regs[1] == 'uniform') {
-            $nbr = $regs[2] + ($regs[3]-$regs[2])*mt_rand()/mt_getrandmax();
+            $nbr = $regs[2] + ($regs[3] - $regs[2]) * mt_rand() / mt_getrandmax();
             return sprintf("%.".$regs[4].'f', $nbr);
 
         } else if ($regs[1] == 'loguniform') {
             $log0 = log(abs($regs[2])); // It would have worked the other way to.
-            $nbr = exp($log0 + (log(abs($regs[3])) - $log0)*mt_rand()/mt_getrandmax());
+            $nbr = exp($log0 + (log(abs($regs[3])) - $log0) * mt_rand() / mt_getrandmax());
             return sprintf("%.".$regs[4].'f', $nbr);
 
         } else {
@@ -1071,14 +1071,14 @@ public function comment_on_datasetitems($qtypeobj, $questionid, $questiontext,
             $answers, $data, $number) {
         global $DB;
         $comment = new stdClass();
-        $comment->stranswers = array();
+        $comment->stranswers = [];
         $comment->outsidelimit = false;
-        $comment->answers = array();
+        $comment->answers = [];
         // Find a default unit.
         $unit = '';
         if (!empty($questionid)) {
             $units = $DB->get_records('question_numerical_units',
-                array('question' => $questionid, 'multiplier' => 1.0),
+                ['question' => $questionid, 'multiplier' => 1.0],
                 'id ASC', '*', 0, 1);
             if ($units) {
                 $unit = reset($units);
@@ -1088,7 +1088,7 @@ public function comment_on_datasetitems($qtypeobj, $questionid, $questiontext,
 
         $answers = fullclone($answers);
         $delimiter = ': ';
-        $virtualqtype =  $qtypeobj->get_virtual_qtype();
+        $virtualqtype = $qtypeobj->get_virtual_qtype();
         foreach ($answers as $key => $answer) {
             $error = qtype_calculated_find_formula_errors($answer->answer);
             if ($error) {
@@ -1121,8 +1121,8 @@ public function comment_on_datasetitems($qtypeobj, $questionid, $questiontext,
                 $correcttrue = new stdClass();
                 $correcttrue->correct = $formattedanswer->answer;
                 $correcttrue->true = '';
-                if ($formattedanswer->answer < $answer->min ||
-                        $formattedanswer->answer > $answer->max) {
+                if ((float) $formattedanswer->answer < $answer->min ||
+                    (float) $formattedanswer->answer > $answer->max) {
                     $comment->outsidelimit = true;
                     $comment->answers[$key] = $key;
                     $comment->stranswers[$key] .=
@@ -1142,11 +1142,11 @@ public function comment_on_datasetitems($qtypeobj, $questionid, $questiontext,
     }
 
     public function tolerance_types() {
-        return array(
+        return [
             '1' => get_string('relative', 'qtype_numerical'),
             '2' => get_string('nominal', 'qtype_numerical'),
-            '3' => get_string('geometric', 'qtype_numerical')
-        );
+            '3' => get_string('geometric', 'qtype_numerical'),
+        ];
     }
 
     public function dataset_options($form, $name, $mandatory = true,
@@ -1166,18 +1166,18 @@ public function dataset_options($form, $name, $mandatory = true,
         }
         if (!$selected) {
             if ($mandatory) {
-                $selected =  "1-0-{$name}"; // Default.
+                $selected = "1-0-{$name}"; // Default.
             } else {
                 $selected = '0'; // Default.
             }
         }
-        return array($options, $selected);
+        return [$options, $selected];
     }
 
     public function construct_dataset_menus($form, $mandatorydatasets,
             $optionaldatasets) {
         global $OUTPUT;
-        $datasetmenus = array();
+        $datasetmenus = [];
         foreach ($mandatorydatasets as $datasetname) {
             if (!isset($datasetmenus[$datasetname])) {
                 list($options, $selected) =
@@ -1249,14 +1249,14 @@ public function substitute_variables_and_eval($str, $dataset) {
     public function get_dataset_definitions($questionid, $newdatasets) {
         global $DB;
         // Get the existing datasets for this question.
-        $datasetdefs = array();
+        $datasetdefs = [];
         if (!empty($questionid)) {
             global $CFG;
             $sql = "SELECT i.*
                       FROM {question_datasets} d, {question_dataset_definitions} i
                      WHERE d.question = ? AND d.datasetdefinition = i.id
                   ORDER BY i.id";
-            if ($records = $DB->get_records_sql($sql, array($questionid))) {
+            if ($records = $DB->get_records_sql($sql, [$questionid])) {
                 foreach ($records as $r) {
                     $datasetdefs["{$r->type}-{$r->category}-{$r->name}"] = $r;
                 }
@@ -1288,7 +1288,7 @@ public function save_dataset_definitions($form) {
         // Save synchronize.
 
         if (empty($form->dataset)) {
-            $form->dataset = array();
+            $form->dataset = [];
         }
         // Save datasets.
         $datasetdefinitions = $this->get_dataset_definitions($form->id, $form->dataset);
@@ -1300,13 +1300,13 @@ public function save_dataset_definitions($form) {
                 if (!isset($tmpdatasets[$defid])) {
                     // This dataset is not used any more, delete it.
                     $DB->delete_records('question_datasets',
-                            array('question' => $form->id, 'datasetdefinition' => $datasetdef->id));
+                            ['question' => $form->id, 'datasetdefinition' => $datasetdef->id]);
                     if ($datasetdef->category == 0) {
                         // Question local dataset.
                         $DB->delete_records('question_dataset_definitions',
-                                array('id' => $datasetdef->id));
+                                ['id' => $datasetdef->id]);
                         $DB->delete_records('question_dataset_items',
-                                array('definition' => $datasetdef->id));
+                                ['definition' => $datasetdef->id]);
                     }
                 }
                 // This has already been saved or just got deleted.
@@ -1324,12 +1324,12 @@ public function save_dataset_definitions($form) {
                 if ($olderdatasetdefs = $DB->get_records_select('question_dataset_definitions',
                         'type = ? AND name = ? AND category = ? AND id < ?
                         ORDER BY id DESC',
-                        array($datasetdef->type, $datasetdef->name,
-                                $datasetdef->category, $datasetdef->id))) {
+                        [$datasetdef->type, $datasetdef->name,
+                                $datasetdef->category, $datasetdef->id])) {
 
                     while ($olderdatasetdef = array_shift($olderdatasetdefs)) {
                         $DB->delete_records('question_dataset_definitions',
-                                array('id' => $datasetdef->id));
+                                ['id' => $datasetdef->id]);
                         $datasetdef = $olderdatasetdef;
                     }
                 }
@@ -1348,13 +1348,13 @@ public function save_dataset_definitions($form) {
         if (!empty($datasetdefinitions)) {
             foreach ($datasetdefinitions as $def) {
                 $DB->delete_records('question_datasets',
-                        array('question' => $form->id, 'datasetdefinition' => $def->id));
+                        ['question' => $form->id, 'datasetdefinition' => $def->id]);
 
                 if ($def->category == 0) { // Question local dataset.
                     $DB->delete_records('question_dataset_definitions',
-                            array('id' => $def->id));
+                            ['id' => $def->id]);
                     $DB->delete_records('question_dataset_items',
-                            array('definition' => $def->id));
+                            ['definition' => $def->id]);
                 }
             }
         }
@@ -1427,12 +1427,12 @@ public function save_as_new_dataset_definitions($form, $initialid) {
                 if ($olderdatasetdefs = $DB->get_records_select('question_dataset_definitions',
                         "type = ? AND " . $DB->sql_equal('name', '?') . " AND category = ? AND id < ?
                         ORDER BY id DESC",
-                        array($datasetdef->type, $datasetdef->name,
-                                $datasetdef->category, $datasetdef->id))) {
+                        [$datasetdef->type, $datasetdef->name,
+                                $datasetdef->category, $datasetdef->id])) {
 
                     while ($olderdatasetdef = array_shift($olderdatasetdefs)) {
                         $DB->delete_records('question_dataset_definitions',
-                                array('id' => $datasetdef->id));
+                                ['id' => $datasetdef->id]);
                         $datasetdef = $olderdatasetdef;
                     }
                 }
@@ -1451,13 +1451,13 @@ public function save_as_new_dataset_definitions($form, $initialid) {
         if (!empty($datasetdefinitions)) {
             foreach ($datasetdefinitions as $def) {
                 $DB->delete_records('question_datasets',
-                        array('question' => $form->id, 'datasetdefinition' => $def->id));
+                        ['question' => $form->id, 'datasetdefinition' => $def->id]);
 
                 if ($def->category == 0) { // Question local dataset.
                     $DB->delete_records('question_dataset_definitions',
-                            array('id' => $def->id));
+                            ['id' => $def->id]);
                     $DB->delete_records('question_dataset_items',
-                            array('definition' => $def->id));
+                            ['definition' => $def->id]);
                 }
             }
         }
@@ -1478,13 +1478,13 @@ public function pick_question_dataset($question, $datasetitem) {
                     AND q.datasetdefinition = d.id
                     AND d.id = i.definition
                     AND i.itemnumber = ?
-               ORDER BY i.id DESC ", array($question->id, $datasetitem))) {
+               ORDER BY i.id DESC ", [$question->id, $datasetitem])) {
             $a = new stdClass();
             $a->id = $question->id;
             $a->item = $datasetitem;
             throw new \moodle_exception('cannotgetdsfordependent', 'question', '', $a);
         }
-        $dataset = Array();
+        $dataset = [];
         foreach ($dataitems as $id => $dataitem) {
             if (!isset($dataset[$dataitem->name])) {
                 $dataset[$dataitem->name] = $dataitem->value;
@@ -1510,14 +1510,14 @@ public function dataset_options_from_database($form, $name, $prefix = '',
             $sql = "SELECT a.*
                 FROM {question_dataset_definitions} a, {question_datasets} b
                WHERE a.id = b.datasetdefinition AND a.type = '1' AND b.question = ? AND " . $DB->sql_equal('a.name', '?');
-            $currentdatasetdef = $DB->get_record_sql($sql, array($form->id, $name));
+            $currentdatasetdef = $DB->get_record_sql($sql, [$form->id, $name]);
             if (!$currentdatasetdef) {
                 $currentdatasetdef = new stdClass();
                 $currentdatasetdef->type = '0';
             }
             $key = "{$type}-0-{$name}";
             if ($currentdatasetdef->type == $type
-                    and $currentdatasetdef->category == 0) {
+                    && $currentdatasetdef->category == 0) {
                 $options[$key] = get_string($prefix."keptlocal{$type}", $langfile);
             } else {
                 $options[$key] = get_string($prefix."newlocal{$type}", $langfile);
@@ -1531,7 +1531,7 @@ public function dataset_options_from_database($form, $name, $prefix = '',
             WHERE a.id = b.datasetdefinition
             AND a.type = '1'
             AND a.category = ?
-            AND " . $DB->sql_equal('a.name', '?'), array($form->category, $name));
+            AND " . $DB->sql_equal('a.name', '?'), [$form->category, $name]);
         $type = 1;
         $key = "{$type}-{$form->category}-{$name}";
         if (!empty($categorydatasetdefs)) {
@@ -1546,9 +1546,9 @@ public function dataset_options_from_database($form, $name, $prefix = '',
             $options[$key] = get_string($prefix."newcategory{$type}", $langfile);
         }
         // All done!
-        return array($options, $currentdatasetdef->type
+        return [$options, $currentdatasetdef->type
             ? "{$currentdatasetdef->type}-{$currentdatasetdef->category}-{$name}"
-            : '');
+            : ''];
     }
 
     /**
@@ -1582,13 +1582,13 @@ public function find_formulas($text) {
      */
     public function get_dataset_definitions_category($form) {
         global $CFG, $DB;
-        $datasetdefs = array();
+        $datasetdefs = [];
         $lnamemax = 30;
         if (!empty($form->category)) {
             $sql = "SELECT i.*, d.*
                       FROM {question_datasets} d, {question_dataset_definitions} i
                      WHERE i.id = d.datasetdefinition AND i.category = ?";
-            if ($records = $DB->get_records_sql($sql, array($form->category))) {
+            if ($records = $DB->get_records_sql($sql, [$form->category])) {
                 foreach ($records as $r) {
                     if (!isset ($datasetdefs["{$r->name}"])) {
                         $datasetdefs["{$r->name}"] = $r->itemcount;
@@ -1608,7 +1608,7 @@ public function get_dataset_definitions_category($form) {
      */
     public function print_dataset_definitions_category($form) {
         global $CFG, $DB;
-        $datasetdefs = array();
+        $datasetdefs = [];
         $lnamemax = 22;
         $namestr          = get_string('name');
         $rangeofvaluestr  = get_string('minmax', 'qtype_calculated');
@@ -1622,7 +1622,7 @@ public function print_dataset_definitions_category($form) {
         {question_dataset_definitions} i
         WHERE i.id = d.datasetdefinition
         AND i.category = ?";
-            if ($records = $DB->get_records_sql($sql, array($category))) {
+            if ($records = $DB->get_records_sql($sql, [$category])) {
                 foreach ($records as $r) {
                     $sql1 = "SELECT q.*
                                FROM {question} q
@@ -1630,12 +1630,12 @@ public function print_dataset_definitions_category($form) {
                     if (!isset ($datasetdefs["{$r->type}-{$r->category}-{$r->name}"])) {
                         $datasetdefs["{$r->type}-{$r->category}-{$r->name}"] = $r;
                     }
-                    if ($questionb = $DB->get_records_sql($sql1, array($r->question))) {
+                    if ($questionb = $DB->get_records_sql($sql1, [$r->question])) {
                         if (!isset ($datasetdefs["{$r->type}-{$r->category}-{$r->name}"]->questions[$r->question])) {
                             $datasetdefs["{$r->type}-{$r->category}-{$r->name}"]->questions[$r->question] = new stdClass();
                         }
-                        $datasetdefs["{$r->type}-{$r->category}-{$r->name}"]->questions[
-                                $r->question]->name = $questionb[$r->question]->name;
+                        $datasetdefs["{$r->type}-{$r->category}-{$r->name}"]->questions[$r->question]->name =
+                            $questionb[$r->question]->name;
                     }
                 }
             }
@@ -1680,8 +1680,7 @@ public function print_dataset_definitions_category($form) {
      * @param int $characterlimit the character limit.
      * @return string
      */
-    public function get_short_question_name($stringtoshorten, $characterlimit)
-    {
+    public function get_short_question_name($stringtoshorten, $characterlimit) {
         if (!empty($stringtoshorten)) {
             $returnstring = format_string($stringtoshorten);
             if (strlen($returnstring) > $characterlimit) {
@@ -1703,7 +1702,7 @@ public function get_short_question_name($stringtoshorten, $characterlimit)
 
     public function print_dataset_definitions_category_shared($question, $datasetdefsq) {
         global $CFG, $DB;
-        $datasetdefs = array();
+        $datasetdefs = [];
         $lnamemax = 22;
         $namestr          = get_string('name', 'quiz');
         $rangeofvaluestr  = get_string('minmax', 'qtype_calculated');
@@ -1715,7 +1714,7 @@ public function print_dataset_definitions_category_shared($question, $datasetdef
             $sql = "SELECT i.*, d.*
                       FROM {question_datasets} d, {question_dataset_definitions} i
                      WHERE i.id = d.datasetdefinition AND i.category = ?";
-            if ($records = $DB->get_records_sql($sql, array($category))) {
+            if ($records = $DB->get_records_sql($sql, [$category])) {
                 foreach ($records as $r) {
                     $key = "{$r->type}-{$r->category}-{$r->name}";
                     $sql1 = "SELECT q.*
@@ -1724,7 +1723,7 @@ public function print_dataset_definitions_category_shared($question, $datasetdef
                     if (!isset($datasetdefs[$key])) {
                         $datasetdefs[$key] = $r;
                     }
-                    if ($questionb = $DB->get_records_sql($sql1, array($r->question))) {
+                    if ($questionb = $DB->get_records_sql($sql1, [$r->question])) {
                         $datasetdefs[$key]->questions[$r->question] = new stdClass();
                         $datasetdefs[$key]->questions[$r->question]->name =
                                 $questionb[$r->question]->name;
@@ -1792,7 +1791,7 @@ public function get_virtual_qtype() {
     }
 
     public function get_possible_responses($questiondata) {
-        $responses = array();
+        $responses = [];
 
         $virtualqtype = $this->get_virtual_qtype();
         $unit = $virtualqtype->get_default_numerical_unit($questiondata);
@@ -1825,7 +1824,7 @@ public function get_possible_responses($questiondata) {
 
         $responses[null] = question_possible_response::no_response();
 
-        return array($questiondata->id => $responses);
+        return [$questiondata->id => $responses];
     }
 
     public function move_files($questionid, $oldcontextid, $newcontextid) {
@@ -1910,7 +1909,7 @@ function qtype_calculated_calculate_answer($formula, $individualdata,
                 $answer .= (1 == strlen($answer) ? '.' : '')
                     . '00000000000000000000000000000000000000000x';
                 $calculated->answer = $sign
-                    .substr($answer, 0, $answerlength +1).$exponent;
+                    .substr($answer, 0, $answerlength + 1).$exponent;
             }
         } else {
             // Stick to plain numeric format.
@@ -1921,7 +1920,7 @@ function qtype_calculated_calculate_answer($formula, $individualdata,
                 // Could be an idea to add some zeros here.
                 $answer .= (preg_match('~^[0-9]*$~', $answer) ? '.' : '')
                     . '00000000000000000000000000000000000000000x';
-                $oklen = $answerlength + ($p10 < 1 ? 2-$p10 : 1);
+                $oklen = $answerlength + ($p10 < 1 ? 2 - $p10 : 1);
                 $calculated->answer = $sign.substr($answer, 0, $oklen);
             }
         }
@@ -1980,7 +1979,7 @@ function qtype_calculated_find_formula_errors($formula) {
                 }
                 break;
 
-                // Single argument functions (the most common case).
+            // Single argument functions (the most common case).
             case 'abs': case 'acos': case 'acosh': case 'asin': case 'asinh':
             case 'atan': case 'atanh': case 'bindec': case 'ceil': case 'cos':
             case 'cosh': case 'decbin': case 'decoct': case 'deg2rad':
@@ -1995,23 +1994,23 @@ function qtype_calculated_find_formula_errors($formula) {
 
                 // Functions that take one or two arguments.
             case 'log': case 'round':
-                if (!empty($regs[5]) || empty($regs[3])) {
-                    return get_string('functiontakesoneortwoargs', 'qtype_calculated', $regs[2]);
-                }
+                    if (!empty($regs[5]) || empty($regs[3])) {
+                        return get_string('functiontakesoneortwoargs', 'qtype_calculated', $regs[2]);
+                    }
                 break;
 
                 // Functions that must have two arguments.
             case 'atan2': case 'fmod': case 'pow':
-                if (!empty($regs[5]) || empty($regs[4])) {
-                    return get_string('functiontakestwoargs', 'qtype_calculated', $regs[2]);
-                }
+                        if (!empty($regs[5]) || empty($regs[4])) {
+                            return get_string('functiontakestwoargs', 'qtype_calculated', $regs[2]);
+                        }
                 break;
 
                 // Functions that take two or more arguments.
             case 'min': case 'max':
-                if (empty($regs[4])) {
-                    return get_string('functiontakesatleasttwo', 'qtype_calculated', $regs[2]);
-                }
+                    if (empty($regs[4])) {
+                        return get_string('functiontakesatleasttwo', 'qtype_calculated', $regs[2]);
+                    }
                 break;
 
             default:
@@ -2045,7 +2044,7 @@ function qtype_calculated_find_formula_errors($formula) {
 function qtype_calculated_find_formula_errors_in_text($text) {
     $formulas = question_bank::get_qtype('calculated')->find_formulas($text);
 
-    $errors = array();
+    $errors = [];
     foreach ($formulas as $match) {
         $error = qtype_calculated_find_formula_errors($match);
         if ($error) {
diff --git a/question/type/calculated/tests/helper.php b/question/type/calculated/tests/helper.php
index 623ed446fd031..cbbe06180217b 100644
--- a/question/type/calculated/tests/helper.php
+++ b/question/type/calculated/tests/helper.php
@@ -41,7 +41,7 @@
  */
 class qtype_calculated_test_helper extends question_test_helper {
     public function get_test_questions() {
-        return array('sum');
+        return ['sum', 'mult'];
     }
 
     /**
@@ -70,15 +70,15 @@ public function make_calculated_question_sum() {
         $q->unitdisplay = qtype_numerical::UNITNONE;
         $q->unitgradingtype = 0;
         $q->unitpenalty = 0;
-        $q->ap = new qtype_numerical_answer_processor(array());
+        $q->ap = new qtype_numerical_answer_processor([]);
         $q->synchronised = false;
 
-        $q->datasetloader = new qtype_calculated_test_dataset_loader(0, array(
-            array('a' => 1, 'b' => 5),
-            array('a' => 3, 'b' => 4),
-            array('a' => 3, 'b' => 0.01416),
-            array('a' => 31, 'b' => 0.01416),
-        ));
+        $q->datasetloader = new qtype_calculated_test_dataset_loader(0, [
+            ['a' => 1, 'b' => 5],
+            ['a' => 3, 'b' => 4],
+            ['a' => 3, 'b' => 0.01416],
+            ['a' => 31, 'b' => 0.01416],
+        ]);
 
         return $q;
     }
@@ -115,7 +115,7 @@ public function get_calculated_question_data_sum() {
             $answer->correctanswerformat = 1;
         }
 
-        $qdata->options->units = array();
+        $qdata->options->units = [];
 
         return $qdata;
     }
@@ -138,24 +138,24 @@ public function get_calculated_question_form_data_sum() {
         $fromform->unitgradingtypes = '1';
         $fromform->unitsleft = '0';
         $fromform->nounits = 1;
-        $fromform->multiplier = array();
+        $fromform->multiplier = [];
         $fromform->multiplier[0] = '1.0';
         $fromform->synchronize = 0;
         $fromform->answernumbering = 0;
         $fromform->shuffleanswers = 0;
 
         $fromform->noanswers = 6;
-        $fromform->answer = array();
+        $fromform->answer = [];
         $fromform->answer[0] = '{a} + {b}';
         $fromform->answer[1] = '{a} - {b}';
         $fromform->answer[2] = '*';
 
-        $fromform->fraction = array();
+        $fromform->fraction = [];
         $fromform->fraction[0] = '1.0';
         $fromform->fraction[1] = '0.0';
         $fromform->fraction[2] = '0.0';
 
-        $fromform->tolerance = array();
+        $fromform->tolerance = [];
         $fromform->tolerance[0] = 0.001;
         $fromform->tolerance[1] = 0.001;
         $fromform->tolerance[2] = 0;
@@ -172,16 +172,16 @@ public function get_calculated_question_form_data_sum() {
         $fromform->correctanswerformat[1] = 1;
         $fromform->correctanswerformat[2] = 1;
 
-        $fromform->feedback = array();
-        $fromform->feedback[0] = array();
+        $fromform->feedback = [];
+        $fromform->feedback[0] = [];
         $fromform->feedback[0]['format'] = FORMAT_HTML;
         $fromform->feedback[0]['text'] = 'Very good.';
 
-        $fromform->feedback[1] = array();
+        $fromform->feedback[1] = [];
         $fromform->feedback[1]['format'] = FORMAT_HTML;
         $fromform->feedback[1]['text'] = 'Add. not subtract!';
 
-        $fromform->feedback[2] = array();
+        $fromform->feedback[2] = [];
         $fromform->feedback[2]['format'] = FORMAT_HTML;
         $fromform->feedback[2]['text'] = 'Completely wrong.';
 
@@ -189,6 +189,149 @@ public function get_calculated_question_form_data_sum() {
 
         return $fromform;
     }
+
+    /**
+     * Makes a calculated question about multiplying two numbers.
+     *
+     * @return qtype_calculated_question
+     * @throws coding_exception
+     */
+    public function make_calculated_question_mult() {
+        question_bank::load_question_definition_classes('calculated');
+        $q = new qtype_calculated_question();
+        test_question_maker::initialise_a_question($q);
+        $q->name = 'Simple multiplication';
+        $q->questiontext = 'What is {a} * {b}?';
+        $q->generalfeedback = 'Generalfeedback: {={a} * {b}} is the right answer.';
+
+        $q->answers = [
+            13 => new \qtype_calculated\qtype_calculated_answer(13, '{a} * {b}', 1.0, 'Positive.', FORMAT_HTML, 0),
+            14 => new \qtype_calculated\qtype_calculated_answer(14, '-{a} * {b}', 0.0, 'Negative.', FORMAT_HTML, 0),
+        ];
+        foreach ($q->answers as $answer) {
+            $answer->correctanswerlength = 2;
+            $answer->correctanswerformat = 1;
+        }
+
+        $q->qtype = question_bank::get_qtype('calculated');
+        $q->unitdisplay = qtype_numerical::UNITOPTIONAL;
+        $q->unitgradingtype = 0;
+        $q->unitpenalty = 0;
+        $q->unit = 'cm';
+        $q->ap = new qtype_numerical_answer_processor([]);
+        $q->synchronised = false;
+
+        $q->datasetloader = new qtype_calculated_test_dataset_loader(0, [
+            ['a' => 1, 'b' => 5],
+            ['a' => 3, 'b' => 4],
+            ['a' => 3, 'b' => 0.01416],
+            ['a' => 31, 'b' => 0.01416],
+        ]);
+
+        return $q;
+    }
+
+    /**
+     * Makes a calculated question about multiplying two numbers.
+     *
+     * @return qtype_calculated_question
+     * @throws coding_exception
+     */
+    public function get_calculated_question_data_mult() {
+        question_bank::load_question_definition_classes('calculated');
+        $qdata = new stdClass();
+        test_question_maker::initialise_question_data($qdata);
+
+        $qdata->qtype = 'calculated';
+        $qdata->name = 'Simple multiplication';
+        $qdata->questiontext = 'What is {a} * {b}?';
+        $qdata->generalfeedback = 'Generalfeedback: {={a} * {b}} is the right answer.';
+        $qdata->status = \core_question\local\bank\question_version_status::QUESTION_STATUS_READY;
+
+        $qdata->options = new stdClass();
+        $qdata->options->unitgradingtype = 0;
+        $qdata->options->unitpenalty = 0.0;
+        $qdata->options->showunits = qtype_numerical::UNITOPTIONAL;
+        $qdata->unit = 'cm';
+        $qdata->options->unitsleft = 0;
+        $qdata->options->synchronize = 0;
+
+        $qdata->options->answers = [
+            13 => new \qtype_calculated\qtype_calculated_answer(13, '{a} * {b}', 1.0, 'Positive.', FORMAT_HTML, 0.001),
+            14 => new \qtype_calculated\qtype_calculated_answer(14, '-{a} * {b}', 0.0, 'Negative.', FORMAT_HTML, 0.001),
+        ];
+        foreach ($qdata->options->answers as $answer) {
+            $answer->correctanswerlength = 2;
+            $answer->correctanswerformat = 1;
+        }
+
+        $qdata->options->units = [];
+
+        return $qdata;
+    }
+
+    /**
+     * Makes a calculated question about multiplying two numbers.
+     *
+     * @return qtype_calculated_question
+     * @throws coding_exception
+     */
+    public function get_calculated_question_form_data_mult() {
+        question_bank::load_question_definition_classes('calculated');
+        $fromform = new stdClass();
+
+        $fromform->name = 'Simple multiplication';
+        $fromform->questiontext = 'What is {a} * {b}?';
+        $fromform->defaultmark = 1.0;
+        $fromform->generalfeedback = 'Generalfeedback: {={a} * {b}} is the right answer.';
+
+        $fromform->unitrole = '0';
+        $fromform->unitpenalty = 0.1;
+        $fromform->unitgradingtypes = '1';
+        $fromform->unitsleft = '0';
+        $fromform->nounits = 1;
+        $fromform->multiplier = [];
+        $fromform->multiplier[0] = '1.0';
+        $fromform->synchronize = 0;
+        $fromform->answernumbering = 0;
+        $fromform->shuffleanswers = 0;
+
+        $fromform->noanswers = 6;
+        $fromform->answer = [];
+        $fromform->answer[0] = '{a} * {b}';
+        $fromform->answer[1] = '-{a} * {b}';
+
+        $fromform->fraction = [];
+        $fromform->fraction[0] = '1.0';
+        $fromform->fraction[1] = '0.0';
+
+        $fromform->tolerance = [];
+        $fromform->tolerance[0] = 0.001;
+        $fromform->tolerance[1] = 0.001;
+
+        $fromform->tolerancetype[0] = 1;
+        $fromform->tolerancetype[1] = 1;
+
+        $fromform->correctanswerlength[0] = 2;
+        $fromform->correctanswerlength[1] = 2;
+
+        $fromform->correctanswerformat[0] = 1;
+        $fromform->correctanswerformat[1] = 1;
+
+        $fromform->feedback = [];
+        $fromform->feedback[0] = [];
+        $fromform->feedback[0]['format'] = FORMAT_HTML;
+        $fromform->feedback[0]['text'] = 'Positive.';
+
+        $fromform->feedback[1] = [];
+        $fromform->feedback[1]['format'] = FORMAT_HTML;
+        $fromform->feedback[1]['text'] = 'Negative.';
+
+        $fromform->status = \core_question\local\bank\question_version_status::QUESTION_STATUS_READY;
+
+        return $fromform;
+    }
+
 }
 
 
@@ -199,9 +342,9 @@ public function get_calculated_question_form_data_sum() {
  * @copyright  2011 The Open University
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
-class qtype_calculated_test_dataset_loader extends qtype_calculated_dataset_loader{
+class qtype_calculated_test_dataset_loader extends qtype_calculated_dataset_loader {
     protected $valuesets;
-    protected $aresynchronised = array();
+    protected $aresynchronised = [];
 
     public function __construct($questionid, array $valuesets) {
         parent::__construct($questionid);
diff --git a/question/type/calculated/tests/question_test.php b/question/type/calculated/tests/question_test.php
index 0d6db2f3c2854..44e73c8487f5a 100644
--- a/question/type/calculated/tests/question_test.php
+++ b/question/type/calculated/tests/question_test.php
@@ -16,7 +16,9 @@
 
 namespace qtype_calculated;
 
+use qtype_calculated;
 use question_attempt_step;
+use question_bank;
 use question_classified_response;
 use question_display_options;
 use question_state;
@@ -36,74 +38,99 @@
  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 class question_test extends \advanced_testcase {
-    public function test_is_complete_response() {
+    /**
+     * Test is complete response
+     *
+     * @covers \qtype_calculated
+     */
+    public function test_is_complete_response(): void {
         $question = \test_question_maker::make_question('calculated');
 
-        $this->assertFalse($question->is_complete_response(array()));
-        $this->assertTrue($question->is_complete_response(array('answer' => '0')));
-        $this->assertTrue($question->is_complete_response(array('answer' => 0)));
-        $this->assertFalse($question->is_complete_response(array('answer' => 'test')));
+        $this->assertFalse($question->is_complete_response([]));
+        $this->assertTrue($question->is_complete_response(['answer' => '0']));
+        $this->assertTrue($question->is_complete_response(['answer' => 0]));
+        $this->assertFalse($question->is_complete_response(['answer' => 'test']));
     }
 
-    public function test_is_gradable_response() {
+    /**
+     * Test is gradable response
+     *
+     * @covers \qtype_calculated
+     */
+    public function test_is_gradable_response(): void {
         $question = \test_question_maker::make_question('calculated');
 
-        $this->assertFalse($question->is_gradable_response(array()));
-        $this->assertTrue($question->is_gradable_response(array('answer' => '0')));
-        $this->assertTrue($question->is_gradable_response(array('answer' => 0)));
-        $this->assertTrue($question->is_gradable_response(array('answer' => 'test')));
+        $this->assertFalse($question->is_gradable_response([]));
+        $this->assertTrue($question->is_gradable_response(['answer' => '0']));
+        $this->assertTrue($question->is_gradable_response(['answer' => 0]));
+        $this->assertTrue($question->is_gradable_response(['answer' => 'test']));
     }
 
-    public function test_grading() {
+    /**
+     * Test grading
+     *
+     * @covers \qtype_calculated
+     */
+    public function test_grading(): void {
         $question = \test_question_maker::make_question('calculated');
         $question->start_attempt(new question_attempt_step(), 1);
         $values = $question->vs->get_values();
 
-        $this->assertEquals(array(0, question_state::$gradedwrong),
-                $question->grade_response(array('answer' => $values['a'] - $values['b'])));
-        $this->assertEquals(array(1, question_state::$gradedright),
-                $question->grade_response(array('answer' => $values['a'] + $values['b'])));
+        $this->assertEquals([0, question_state::$gradedwrong],
+                $question->grade_response(['answer' => $values['a'] - $values['b']]));
+        $this->assertEquals([1, question_state::$gradedright],
+                $question->grade_response(['answer' => $values['a'] + $values['b']]));
     }
 
-    public function test_get_correct_response() {
+    /**
+     * Test get correct response
+     *
+     * @covers \qtype_calculated
+     */
+    public function test_get_correct_response(): void {
         // Testing with 3.0 + 0.1416.
         $question = \test_question_maker::make_question('calculated');
         $question->start_attempt(new question_attempt_step(), 3);
         $values = $question->vs->get_values();
-        $this->assertSame(array('answer' => '3.01' ), $question->get_correct_response());
+        $this->assertSame(['answer' => '3.01' ], $question->get_correct_response());
         foreach ($question->answers as $answer) {
             $answer->correctanswerlength = 2;
             $answer->correctanswerformat = 2;
         }
-        $this->assertSame(array('answer' => '3.0' ), $question->get_correct_response());
+        $this->assertSame(['answer' => '3.0' ], $question->get_correct_response());
 
         // Testing with 1.0 + 5.0.
         $question = \test_question_maker::make_question('calculated');
         $question->start_attempt(new question_attempt_step(), 1);
         $values = $question->vs->get_values();
-        $this->assertSame(array('answer' => '6.00' ), $question->get_correct_response());
+        $this->assertSame(['answer' => '6.00' ], $question->get_correct_response());
 
         foreach ($question->answers as $answer) {
             $answer->correctanswerlength = 2;
             $answer->correctanswerformat = 2;
         }
-        $this->assertSame(array('answer' => '6.0' ),
+        $this->assertSame(['answer' => '6.0' ],
                 $question->get_correct_response());
         // Testing with 31.0 + 0.01416 .
         $question = \test_question_maker::make_question('calculated');
         $question->start_attempt(new question_attempt_step(), 4);
         $values = $question->vs->get_values();
-        $this->assertSame(array('answer' => '31.01' ), $question->get_correct_response());
+        $this->assertSame(['answer' => '31.01' ], $question->get_correct_response());
 
         foreach ($question->answers as $answer) {
             $answer->correctanswerlength = 3;
             $answer->correctanswerformat = 2;
         }
-        $this->assertSame(array('answer' => '31.0' ), $question->get_correct_response());
+        $this->assertSame(['answer' => '31.0' ], $question->get_correct_response());
 
     }
 
-    public function test_get_question_summary() {
+    /**
+     * Test get question summary
+     *
+     * @covers \qtype_calculated
+     */
+    public function test_get_question_summary(): void {
         $question = \test_question_maker::make_question('calculated');
         $question->start_attempt(new question_attempt_step(), 1);
         $values = $question->vs->get_values();
@@ -112,65 +139,95 @@ public function test_get_question_summary() {
         $this->assertEquals('What is ' . $values['a'] . ' + ' . $values['b'] . '?', $qsummary);
     }
 
-    public function test_summarise_response() {
+    /**
+     * Test summarise response
+     *
+     * @covers \qtype_calculated
+     */
+    public function test_summarise_response(): void {
         $question = \test_question_maker::make_question('calculated');
         $question->start_attempt(new question_attempt_step(), 1);
         $values = $question->vs->get_values();
 
-        $this->assertEquals('3.1', $question->summarise_response(array('answer' => '3.1')));
+        $this->assertEquals('3.1', $question->summarise_response(['answer' => '3.1']));
     }
 
-    public function test_classify_response() {
+    /**
+     * Test classify response
+     *
+     * @covers \qtype_calculated
+     */
+    public function test_classify_response(): void {
         $question = \test_question_maker::make_question('calculated');
         $question->start_attempt(new question_attempt_step(), 1);
         $values = $question->vs->get_values();
 
-        $this->assertEquals(array(
-                new question_classified_response(13, $values['a'] + $values['b'], 1.0)),
-                $question->classify_response(array('answer' => $values['a'] + $values['b'])));
-        $this->assertEquals(array(
-                new question_classified_response(14, $values['a'] - $values['b'], 0.0)),
-                $question->classify_response(array('answer' => $values['a'] - $values['b'])));
-        $this->assertEquals(array(
-                new question_classified_response(17, 7 * $values['a'], 0.0)),
-                $question->classify_response(array('answer' => 7 * $values['a'])));
-        $this->assertEquals(array(
-                question_classified_response::no_response()),
-                $question->classify_response(array('answer' => '')));
+        $this->assertEquals([
+                new question_classified_response(13, $values['a'] + $values['b'], 1.0)],
+                $question->classify_response(['answer' => $values['a'] + $values['b']]));
+        $this->assertEquals([
+                new question_classified_response(14, $values['a'] - $values['b'], 0.0)],
+                $question->classify_response(['answer' => $values['a'] - $values['b']]));
+        $this->assertEquals([
+                new question_classified_response(17, 7 * $values['a'], 0.0)],
+                $question->classify_response(['answer' => 7 * $values['a']]));
+        $this->assertEquals([
+                question_classified_response::no_response()],
+                $question->classify_response(['answer' => '']));
     }
 
-    public function test_classify_response_no_star() {
+    /**
+     * Test classify response no star
+     *
+     * @covers \qtype_calculated
+     */
+    public function test_classify_response_no_star(): void {
         $question = \test_question_maker::make_question('calculated');
         unset($question->answers[17]);
         $question->start_attempt(new question_attempt_step(), 1);
         $values = $question->vs->get_values();
 
-        $this->assertEquals(array(
-                new question_classified_response(13, $values['a'] + $values['b'], 1.0)),
-                $question->classify_response(array('answer' => $values['a'] + $values['b'])));
-        $this->assertEquals(array(
-                new question_classified_response(14, $values['a'] - $values['b'], 0.0)),
-                $question->classify_response(array('answer' => $values['a'] - $values['b'])));
-        $this->assertEquals(array(
-                new question_classified_response(0, 7 * $values['a'], 0.0)),
-                $question->classify_response(array('answer' => 7 * $values['a'])));
-        $this->assertEquals(array(
-                question_classified_response::no_response()),
-                $question->classify_response(array('answer' => '')));
+        $this->assertEquals([
+                new question_classified_response(13, $values['a'] + $values['b'], 1.0)],
+                $question->classify_response(['answer' => $values['a'] + $values['b']]));
+        $this->assertEquals([
+                new question_classified_response(14, $values['a'] - $values['b'], 0.0)],
+                $question->classify_response(['answer' => $values['a'] - $values['b']]));
+        $this->assertEquals([
+                new question_classified_response(0, 7 * $values['a'], 0.0)],
+                $question->classify_response(['answer' => 7 * $values['a']]));
+        $this->assertEquals([
+                question_classified_response::no_response()],
+                $question->classify_response(['answer' => '']));
     }
 
-    public function test_get_variants_selection_seed_q_not_synchronised() {
+    /**
+     * Test get variants selection seed q not synchronised
+     *
+     * @covers \qtype_calculated
+     */
+    public function test_get_variants_selection_seed_q_not_synchronised(): void {
         $question = \test_question_maker::make_question('calculated');
         $this->assertEquals($question->stamp, $question->get_variants_selection_seed());
     }
 
-    public function test_get_variants_selection_seed_q_synchronised_datasets_not() {
+    /**
+     * Test get variants selection seed q synchronised datasets not
+     *
+     * @covers \qtype_calculated
+     */
+    public function test_get_variants_selection_seed_q_synchronised_datasets_not(): void {
         $question = \test_question_maker::make_question('calculated');
         $question->synchronised = true;
         $this->assertEquals($question->stamp, $question->get_variants_selection_seed());
     }
 
-    public function test_get_variants_selection_seed_q_synchronised() {
+    /**
+     * Test get variants selection seed q synchronised
+     *
+     * @covers \qtype_calculated
+     */
+    public function test_get_variants_selection_seed_q_synchronised(): void {
         $question = \test_question_maker::make_question('calculated');
         $question->synchronised = true;
         $question->datasetloader->set_are_synchronised($question->category, true);
@@ -179,9 +236,11 @@ public function test_get_variants_selection_seed_q_synchronised() {
     }
 
     /**
-     * test_get_question_definition_for_external_rendering
+     * Test get question definition for external rendering
+     *
+     * @covers \qtype_calculated
      */
-    public function test_get_question_definition_for_external_rendering() {
+    public function test_get_question_definition_for_external_rendering(): void {
         $this->resetAfterTest();
 
         $question = \test_question_maker::make_question('calculated');
@@ -196,4 +255,43 @@ public function test_get_question_definition_for_external_rendering() {
         $this->assertEquals(qtype_numerical::UNITNONE, $options['unitdisplay']);
         $this->assertEmpty($options['unitsleft']);
     }
+
+    /**
+     * Test that the grading of negative responses does not show false ERROR.
+     *
+     * @return void
+     * @throws \coding_exception
+     * @throws \dml_exception
+     * @covers \qtype_calculated
+     */
+    public function test_grading_of_negative_responses(): void {
+        global $DB;
+
+        $this->resetAfterTest();
+
+        $qtype = new qtype_calculated();
+
+        // Create a question.
+        $q = \test_question_maker::get_question_data('calculated', 'mult');
+        $q->id = 99;
+
+        // Add units for the question. The issue to test only applies if the answer contains a unit string.
+        $units = [];
+        $unit = new \stdClass();
+        $unit->question = $q->id;
+        $unit->multiplier = 1.0;
+        $unit->unit = "cm";
+        $units[] = $unit;
+        $DB->insert_records("question_numerical_units", $units);
+
+        $qtypeobj = question_bank::get_qtype($qtype->name());
+        $fakedata = ["a" => "5.7", "b" => "3.3"];
+
+        $result = $qtype->comment_on_datasetitems($qtypeobj, $q->id, $q->questiontext, $q->options->answers, $fakedata, 1);
+
+        // Make sure "ERROR" is not part of the answers.
+        foreach ($result->stranswers as $answer) {
+            $this->assertFalse(strstr($answer, "ERROR"), "Assert that 'ERROR' is not part of the answer!");
+        }
+    }
 }