diff --git a/exercises/B-hello-world/README.md b/exercises/B-hello-world/README.md
index 8c704fb43..5f03737e3 100644
--- a/exercises/B-hello-world/README.md
+++ b/exercises/B-hello-world/README.md
@@ -14,5 +14,5 @@ Inside of `exercise.js` there's a line of code that will print "Hello world!".
 
 - Try to `console.log()` something different. For example, 'Hello World. I just started learning JavaScript!'.
 - Try to console.log() several things at once.
-- What happens when you get rid of the quote marks?
-- What happens when you console.log() just a number without quotes?
+- What happens when you get rid of the quote marks? SyntaxError: missing ) after argument list
+- What happens when you console.log() just a number without quotes? Shows the number in yellow.
\ No newline at end of file
diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..8a6bebef9 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1,6 @@
-console.log("Hello world");
+console.log("Hello World. I just started learning JavaScript!");
+console.log("Hello World. I just started learning JavaScript! 1");
+console.log("Hello World. I just started learning JavaScript! 2");
+console.log("Hello World. I just started learning JavaScript! 3");
+console.log("Hello World. I just started learning JavaScript! 4");
+console.log(1);
\ No newline at end of file
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..64a28a39c 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `greeting`
-
+var greeting = "Hello world";
+console.log(greeting);
 console.log(greeting);
+console.log(greeting);
+
diff --git a/exercises/D-strings/exercise.js b/exercises/D-strings/exercise.js
index 2cffa6a81..e415c83ee 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `message`
-
+var message = "This is a string"
+var typemessage = typeof message
 console.log(message);
+console.log(typemessage);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..d52503298 100644
--- a/exercises/E-strings-concatenation/exercise.js
+++ b/exercises/E-strings-concatenation/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `message`
-
-console.log(message);
+var greetingStart = "Hello, my name is";
+var myname = " Salvador";
+var greeting = greetingStart + myname;
+console.log(greeting);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..650d6e596 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,10 @@
 // Start by creating a variable `message`
+var greetingStart = "My name is ";
+var myname = "Salvador ";
+var greetingMiddle = "and my name is ";
+var nameLength = myname.length;
+var greetingEnd = " characters long"
 
-console.log(message);
+var alltogether = greetingStart + myname + greetingMiddle + nameLength + greetingEnd;
+
+console.log(alltogether);
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..2028668f7 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,4 @@
 const name = " Daniel  ";
+var trim = name.trim();
 
-console.log(message);
+console.log(trim);
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..a3912d632 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,10 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+var students = 15;
+var mentors = 8;
+var numberOfStudents = "Number of students: " + students;
+var numberOfMentors = "Number of mentors: " + mentors;
+var total = "Total numnber of students and mentors: " + (mentors + students);
+
+console.log(numberOfStudents);
+console.log(numberOfMentors);
+console.log(total);
\ No newline at end of file
diff --git a/exercises/I-floats/README.md b/exercises/I-floats/README.md
index bbc9e29c2..44b266b3b 100644
--- a/exercises/I-floats/README.md
+++ b/exercises/I-floats/README.md
@@ -1,8 +1,4 @@
-Numbers can be integers (whole numbers) or floats (numbers with a decimal).
-
-```js
-var preciseAge = 30.612437;
-```
+---
 
 Floats can be rounded to the nearest whole number using the `Math.round` function:
 
@@ -21,3 +17,5 @@ var roughAge = Math.round(preciseAge); // 30
 Percentage students: 65%
 Percentage mentors: 35%
 ```
+
+-
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..3e0aedcbd 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,12 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+var porcentageStudents =
+  (numberOfStudents * 100) / (numberOfStudents + numberOfMentors);
+var porcentageMentors =
+  (numberOfMentors * 100) / (numberOfStudents + numberOfMentors);
+
+var students = Math.round(porcentageStudents);
+var mentors = Math.round(porcentageMentors);
+
+console.log("Percentage students: " + students + "%");
+console.log("Percentage mentors: " + mentors + "%");
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..0047d2daf 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,7 +1,11 @@
 function halve(number) {
   // complete the function here
+  return number / 2;
 }
 
 var result = halve(12);
 
 console.log(result);
+
+console.log(halve(5));
+console.log(halve(10));
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..468d45596 100644
--- a/exercises/J-functions/exercise2.js
+++ b/exercises/J-functions/exercise2.js
@@ -1,5 +1,6 @@
 function triple(number) {
   // complete function here
+  return number * 3;
 }
 
 var result = triple(12);
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..dbd50454d 100644
--- a/exercises/K-functions-parameters/exercise.js
+++ b/exercises/K-functions-parameters/exercise.js
@@ -1,6 +1,7 @@
 // Complete the function so that it takes input parameters
-function multiply() {
+function multiply(a, b) {
   // Calculate the result of the function and return it
+  return a * b;
 }
 
 // Assign the result of calling the function the variable `result`
diff --git a/exercises/K-functions-parameters/exercise2.js b/exercises/K-functions-parameters/exercise2.js
index db7a8904b..e7c787d04 100644
--- a/exercises/K-functions-parameters/exercise2.js
+++ b/exercises/K-functions-parameters/exercise2.js
@@ -1,5 +1,7 @@
 // Declare your function first
-
+function divide(a, b) {
+  return a / b;
+}
 var result = divide(3, 4);
 
 console.log(result);
diff --git a/exercises/K-functions-parameters/exercise3.js b/exercises/K-functions-parameters/exercise3.js
index 537e9f4ec..cfdb5582d 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,4 +1,7 @@
 // Write your function here
+function createGreeting(string) {
+  return "Hello, my name is " + string;
+}
 
 var greeting = createGreeting("Daniel");
 
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..a290e3795 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,9 @@
 // Declare your function first
+function add(a, b) {
+  return a + b;
+}
 
-// Call the function and assign to a variable `sum`
+var sum = add(13, 124);
 
 console.log(sum);
+// Call the function and assign to a variable `sum`
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..8fc9c9b96 100644
--- a/exercises/K-functions-parameters/exercise5.js
+++ b/exercises/K-functions-parameters/exercise5.js
@@ -1,4 +1,7 @@
 // Declare your function here
+function createLongGreeting(string, a) {
+  return "Hello, my name is " + string + " and I'm " + a + " years old";
+}
 
 const greeting = createLongGreeting("Daniel", 30);
 
diff --git a/exercises/L-functions-nested/exercise.js b/exercises/L-functions-nested/exercise.js
index a5d377442..effaf5c2a 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -3,3 +3,14 @@ var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+
+function shout(string) {
+  var uppercase = string.toUpperCase();
+  return "HELLO " + uppercase;
+}
+
+console.log(shout(mentor1));
+console.log(shout(mentor2));
+console.log(shout(mentor3));
+console.log(shout(mentor4));
+console.log(shout(mentor5));
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index a10cc9ac2..87186be4d 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,16 +1,16 @@
 // There are syntax errors in this code - can you fix it to pass the tests?
 
-function addNumbers(a b c) {
+function addNumbers(a, b, c) {
   return a + b + c;
 }
 
-function introduceMe(name, age)
-  return "Hello, my name is " + name "and I am " age + "years old";
-
+function introduceMe(name, age) {
+  return "Hello, my name is " + name + " and I am " + age + " years old";
+}
 function getTotal(a, b) {
-  total = a ++ b;
+  var total = a + b;
 
-  return "The total is total";
+  return "The total is " + total;
 }
 
 /* 
diff --git a/mandatory/2-logic-error.js b/mandatory/2-logic-error.js
index 9cca7603b..37c4ebc15 100644
--- a/mandatory/2-logic-error.js
+++ b/mandatory/2-logic-error.js
@@ -1,16 +1,15 @@
 // The syntax for this function is valid but it has an error, find it and fix it.
 
 function trimWord(word) {
-  return wordtrim();
+  return word.trim();
 }
 
 function getStringLength(word) {
-  return "word".length();
+  return word.length;
 }
 
 function multiply(a, b, c) {
-  a * b * c;
-  return;
+  return a * b * c;
 }
 
 /* 
diff --git a/mandatory/3-function-output.js b/mandatory/3-function-output.js
index 5a953ba60..3e2857096 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,16 +1,17 @@
 // Add comments to explain what this function does. You're meant to use Google!
 function getRandomNumber() {
-  return Math.random() * 10;
+  return Math.random() * 10; // Get a random number and multiply it by 10
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
 function combine2Words(word1, word2) {
-  return word1.concat(word2);
+  return word1.concat(word2); /* Join word1 and word2 */
 }
 
-function concatenate(firstWord, secondWord, thirdWord) {
+function concatenate(string1, string2, string3) {
   // Write the body of this function to concatenate three words together.
   // Look at the test case below to understand what this function is expected to return.
+  return string1.concat(" ", string2, " ", string3);
 }
 
 /* 
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..3462ae3de 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,8 +5,9 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
-
+function calculateSalesTax(num) {
+  return num * 1.2;
+}
 /*
   CURRENCY FORMATTING
   ===================
@@ -17,8 +18,10 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
-
+function addTaxAndFormatCurrency(num) {
+  var total = calculateSalesTax(num).toFixed(2);
+  return "£" + total;
+}
 /* 
 ===================================================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
diff --git a/package.json b/package.json
index 58555936d..778df9683 100644
--- a/package.json
+++ b/package.json
@@ -14,7 +14,9 @@
     "url": "https://github.com/CodeYourFuture/JavaScript-Core-1-Coursework-Week1/issues"
   },
   "jest": {
-    "setupFilesAfterEnv": ["jest-extended"]
+    "setupFilesAfterEnv": [
+      "jest-extended"
+    ]
   },
   "homepage": "https://github.com/CodeYourFuture/JavaScript-Core-1-Coursework-Week1#readme",
   "devDependencies": {