diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..ace307eea 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1,8 @@
-console.log("Hello world");
+console.log("Hello World. I just started learning JavaScript!");
+console.log('Hello World. This is my second JavaScript code!');
+console.log('I am a Web Developer.');
+// console.log(I know how to CODE!); this outputs an error
+console.log("Without Coffee, I can't code.");
+console.log("The is No Hello World without us Developers!");
+console.log("A cup of COFFEE translate into CODE!");
+console.log(10);
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..b625cd4ed 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,3 @@
 // Start by creating a variable `greeting`
-
-console.log(greeting);
+var greeting = "Hello World!";
+console.log(greeting + "\n" + greeting + "\n" + greeting);
diff --git a/exercises/D-strings/exercise.js b/exercises/D-strings/exercise.js
index 2cffa6a81..3772ea23d 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `message`
+var message = "This is a string";
+var messageType = typeof message;
 
 console.log(message);
+console.log(messageType);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..21bf53246 100644
--- a/exercises/E-strings-concatenation/exercise.js
+++ b/exercises/E-strings-concatenation/exercise.js
@@ -1,3 +1,7 @@
 // Start by creating a variable `message`
+var greetingStart = "Hello, my name is ";
+var name = "Ulrich.";
 
-console.log(message);
+var greeting = greetingStart + name;
+
+console.log(greeting);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..3afc48ff8 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `message`
+var name = "Ulrich";
+var nameLength = name.length;
 
-console.log(message);
+console.log("My name is " + name + " and my name is " + nameLength + " characters long.");
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..c1f76bbf7 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,7 @@
 const name = " Daniel  ";
-
-console.log(message);
+var greetingStart = "My name is ";
+var middleMsg = " and my name is ";
+var lastMsg = " characters long.";
+var nameTrim = name.trim();
+var nameLength = name.trim().length;
+console.log(greetingStart + nameTrim + middleMsg + nameLength + lastMsg);
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..a2ed8f532 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,6 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+var numberOfStudents = 15;
+var numberOfMentors = 8;
+var total = numberOfStudents + numberOfMentors;
+
+console.log("Number of students: " + numberOfStudents + "\nNumber of mentors: " + numberOfMentors + "\nTotal number of students and mentors: " + total)
\ No newline at end of file
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..9191e6f27 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,10 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+var total = numberOfStudents + numberOfMentors;
+
+var studentCal = numberOfStudents / total * 100;
+var mentorCal = numberOfMentors / total * 100;
+var studentPercentage = Math.round(studentCal);
+var mentorPercentage = Math.round(mentorCal);
+
+console.log("Percentage students: " + studentPercentage + '%' + "\nPercentage mentors: " + mentorPercentage + '%');
\ No newline at end of file
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..0fc4c3655 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,5 +1,6 @@
 function halve(number) {
   // complete the function here
+  return number / 2;
 }
 
 var result = halve(12);
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..d29e195d9 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..971e7fe69 100644
--- a/exercises/K-functions-parameters/exercise2.js
+++ b/exercises/K-functions-parameters/exercise2.js
@@ -1,4 +1,7 @@
 // Declare your function first
+function divide(a, b){
+    return a / b;
+}
 
 var result = divide(3, 4);
 
diff --git a/exercises/K-functions-parameters/exercise3.js b/exercises/K-functions-parameters/exercise3.js
index 537e9f4ec..fbfbf0c9b 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(name){
+    return "Hello, my name is " + name;
+}
 
 var greeting = createGreeting("Daniel");
 
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..7cefd3c20 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,9 @@
 // Declare your function first
+function adds(a, b){
+    return a + b;
+}
 
 // Call the function and assign to a variable `sum`
+var sum = adds(13, 124);
 
 console.log(sum);
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..ccbcf3946 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(name, age){
+    return "Hello, my name is " + name + " and i'm " + age + " 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..a5d2d0ffe 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -1,5 +1,11 @@
-var mentor1 = "Daniel";
-var mentor2 = "Irina";
-var mentor3 = "Mimi";
-var mentor4 = "Rob";
-var mentor5 = "Yohannes";
+function calculate(num1, num2){
+    return num1 / (num1 + num2) * 100;
+}
+
+function createPercentage(num1, num2) {
+    var student = Math.round(calculate(num1, num2));
+    var mentor = Math.round(calculate(num2, num1));
+    var message = "Percentage students: " + student + "%" + "\nPercentage mentors: " + mentor + "%";
+    return message;
+}
+console.log(createPercentage(15, 8));
\ No newline at end of file
diff --git a/exercises/L-functions-nested/exercise2.js b/exercises/L-functions-nested/exercise2.js
new file mode 100644
index 000000000..b10e8ec22
--- /dev/null
+++ b/exercises/L-functions-nested/exercise2.js
@@ -0,0 +1,22 @@
+var mentor1 = "Daniel";
+var mentor2 = "Irina";
+var mentor3 = "Mimi";
+var mentor4 = "Rob";
+var mentor5 = "Yohannes";
+
+function greeting(){
+    var greet = "HELLO";
+    return greet;
+}
+
+function upperCase() {
+    var capitalLetter1 = mentor1.toUpperCase();
+    var capitalLetter2 = mentor2.toUpperCase();
+    var capitalLetter3 = mentor3.toUpperCase();
+    var capitalLetter4 = mentor4.toUpperCase();
+    var capitalLetter5 = mentor5.toUpperCase();
+    var mentorCap = greeting() + " " + capitalLetter1 + "\n" + greeting() + " " + capitalLetter2 + "\n" + greeting() + " " + capitalLetter3 + "\n" + greeting() + " " + capitalLetter4 + "\n" + greeting() + " " + capitalLetter5;
+    return mentorCap;
+}
+
+console.log(upperCase());
diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index 70a2fe863..91a23f1e0 100644
--- a/extra/1-currency-conversion.js
+++ b/extra/1-currency-conversion.js
@@ -5,7 +5,9 @@
   Write a function that converts a price to USD (exchange rate is 1.4 $ to £)
 */
 
-function convertToUSD() {}
+function convertToUSD(num1) {
+  return num1 * 1.4;
+}
 
 /*
   CURRENCY FORMATTING
@@ -15,7 +17,9 @@ function convertToUSD() {}
   They have also decided that they should add a 1% fee to all foreign transactions, which means you only convert 99% of the £ to BRL.
 */
 
-function convertToBRL() {}
+function convertToBRL(num1) {
+  return num1 * 5.643;
+}
 
 /* ======= TESTS - DO NOT MODIFY ===== 
 There are some Tests in this file that will help you work out if your code is working.
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index 0a21afd1b..28b182e4f 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,16 +1,17 @@
 // 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;
+    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 3c578ad87..1f1245b39 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 getWordLength(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 c9221a200..3e15726cf 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,9 +1,11 @@
 // Add comments to explain what this function does. You're meant to use Google!
+// This function outputs a random number and multiply it by 10,
 function getNumber() {
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
+// This function is joining the word w1 with the word w2, example w1 = hand and w2 = ball, and then the output would be handball
 function s(w1, w2) {
   return w1.concat(w2);
 }
@@ -11,6 +13,7 @@ function s(w1, w2) {
 function concatenate(firstWord, secondWord, thirdWord) {
   // 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 firstWord + " " + secondWord + " " + thirdWord;
 }
 
 /* 
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index c9e41c691..bafbed182 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,9 @@
   Sales tax is 20% of the price of the product
 */
 
-function calculateSalesTax() {}
+function calculateSalesTax(num1) {
+  return num1 / 20 * 24;
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +19,10 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(num2) {
+  const taxes = calculateSalesTax(num2).toFixed(2);
+  return "£" + taxes; 
+}
 
 /* 
 ===================================================