diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..55caa7630 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1,5 @@
-console.log("Hello world");
+console.log("Hello world I just started learning JavaScript!");
+console.log("1");
+console.log(1);
+
+
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..c4da9d78c 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,3 @@
 // Start by creating a variable `greeting`
-
+var greeting = "Hello World";
 console.log(greeting);
diff --git a/exercises/D-strings/exercise.js b/exercises/D-strings/exercise.js
index 2cffa6a81..9e97df5a4 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,4 @@
 // Start by creating a variable `message`
+var message = "This is a string";
 
-console.log(message);
+console.log(message + "\n" + typeof message);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..907e4189e 100644
--- a/exercises/E-strings-concatenation/exercise.js
+++ b/exercises/E-strings-concatenation/exercise.js
@@ -1,3 +1,4 @@
 // Start by creating a variable `message`
-
-console.log(message);
+var myName = "Selahaddin";
+var message = "Hello, my name is ";
+console.log(message + myName);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..fd5fcdab4 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,3 @@
 // Start by creating a variable `message`
-
-console.log(message);
+var myName = "Selahaadin"
+console.log("My name is " + myName + " and my name is " + myName.length + " characters long.");
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..9a5279f70 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,9 @@
-const name = " Daniel  ";
+const myName = " Daniel  ";
 
-console.log(message);
+console.log(
+  "My name is " +
+    myName.trim() +
+    " and my name is " +
+    myName.trim().length +
+    " characters long."
+);
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..a8d3c1f3f 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,7 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+var numberOfStudents = 15;
+var numberOfMentors = 10;
+
+console.log('Number of students: ' + numberOfStudents);
+console.log('Number of mentors: ' + numberOfMentors);
+console.log('Total number of students and mentors: ' + (numberOfStudents + numberOfMentors));
\ No newline at end of file
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..dc70a2855 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,13 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+
+var percentageOfStudents = (numberOfStudents * 100) / (numberOfStudents + numberOfMentors);
+var percentageOfMentors =
+  (numberOfMentors * 100) / (numberOfStudents + numberOfMentors);
+
+console.log( "Percantage students: " +
+    Math.round(percentageOfStudents) 
+    + "%" );
+console.log( "Percentage mentors: " +
+    Math.round(percentageOfMentors)
+    + "%" );
\ No newline at end of file
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..cbf53285c 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,7 +1,8 @@
 function halve(number) {
   // complete the function here
+  return number / 2;
 }
 
 var result = halve(12);
-
+result = halve(1);
 console.log(result);
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..a4eed9d76 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(num1, num2) {
   // Calculate the result of the function and return it
+  return num1 * num2;
 }
 
 // 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..34cebc84a 100644
--- a/exercises/K-functions-parameters/exercise2.js
+++ b/exercises/K-functions-parameters/exercise2.js
@@ -1,5 +1,9 @@
 // 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..8aaea4624 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,5 +1,9 @@
 // Write your function here
 
+function createGreeting(name) {
+  return "Hello, my name is " + name;
+}
+
 var greeting = createGreeting("Daniel");
 
 console.log(greeting);
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..48135de5f 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,9 @@
 // Declare your function first
 
-// Call the function and assign to a variable `sum`
+function add(a, b) {
+    return a + b;
+}
 
+// Call the function and assign to a variable `sum`
+var sum = add(13, 124);
 console.log(sum);
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..a0dbfecae 100644
--- a/exercises/K-functions-parameters/exercise5.js
+++ b/exercises/K-functions-parameters/exercise5.js
@@ -1,5 +1,9 @@
 // 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);
 
 console.log(greeting);
diff --git a/exercises/L-functions-nested/exercise.js b/exercises/L-functions-nested/exercise.js
index a5d377442..69f7819ad 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -1,5 +1,20 @@
+
+function makeUpperCase(str) {
+    return str.toUpperCase();
+}
+
+function shoutyGreeting(firstName) {
+    return "HELLO " + makeUpperCase(firstName);
+}
+
 var mentor1 = "Daniel";
 var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+ 
+console.log(shoutyGreeting(mentor1));
+console.log(shoutyGreeting(mentor2));
+console.log(shoutyGreeting(mentor3));
+console.log(shoutyGreeting(mentor4));
+console.log(shoutyGreeting(mentor5));
\ No newline at end of file
diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index d82e59480..5ffc6d065 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(pound) {
+  return pound * 1.4;
+}
 
 /*
   CURRENCY CONVERSION
@@ -15,7 +17,11 @@ 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(pound) {
+  let fee = pound * 0.01;
+  pound = pound - fee;
+  return parseFloat((pound * 5.7).toFixed(2));
+}
 
 /* ======= 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/extra/2-piping.js b/extra/2-piping.js
index 9c8ebc76a..3e63adbb2 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,26 +16,29 @@
   the final result to the variable goodCode
 */
 
-function add() {
-
+function add(num1,num2) {
+  return num1 + num2;
 }
 
-function multiply() {
-
+function multiply(num1,num2) {
+  return num1 * num2;
 }
 
-function format() {
-
+function format(number) {
+  return '£' + number;
 }
 
 const startingValue = 2;
 
 // Why can this code be seen as bad practice? Comment your answer.
-let badCode =
+// It's hard to read and difficult to debug.
+let badCode = format(multiply(add(startingValue,10),2));
 
 /* BETTER PRACTICE */
 
-let goodCode =
+let goodCode = add(startingValue, 10);
+goodCode = multiply(goodCode, 2);
+goodCode = format(goodCode);
 
 /* ======= 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/extra/3-magic-8-ball.js b/extra/3-magic-8-ball.js
index f3adbefa5..24c6062d1 100644
--- a/extra/3-magic-8-ball.js
+++ b/extra/3-magic-8-ball.js
@@ -47,6 +47,24 @@
 // and return the answer.
 function shakeBall() {
   //Write your code in here
+
+  let veryPositiveAnswers = ["It is certain.","It is decidedly so.", "Without a doubt.", "Yes - definitely.", "You may rely on it."];
+  let positiveAnswers = ["As I see it, yes.", "Most likely.", "Outlook good.", "Yes.", "Signs point to yes."];
+  let negativeAnswers = ["Reply hazy, try again.", "Ask again later.", "Better not tell you now.", "Cannot predict now.", "Concentrate and ask again."];
+  let veryNegativeAnswers = ["Don't count on it.", "My reply is no.", "My sources say no.", "Outlook not so good.", "Very doubtful."];
+
+  let randomNumber = Math.floor(Math.random() * veryPositiveAnswers.length);
+ 
+    let randomAnswer = [
+      veryPositiveAnswers[randomNumber],
+      positiveAnswers[randomNumber],
+      negativeAnswers[randomNumber],
+      veryNegativeAnswers[randomNumber],
+    ];
+
+  let randomNumber2 = Math.floor(Math.random() * randomAnswer.length);
+  console.log("The ball has shaken!");
+  return randomAnswer[randomNumber2];
 }
 
 /* 
@@ -60,6 +78,20 @@ function shakeBall() {
 */
 function checkAnswer(answer) {
   //Write your code in here
+  if (answer === "It is certain." || answer === "It is decidedly so." || answer === "Without a doubt." || answer === "Yes - definitely." || answer === "You may rely on it.") {
+    return "very positive";
+  }
+  else if (answer === "As I see it, yes." || answer === "Most likely." || answer === "Outlook good." || answer === "Yes." || answer === "Signs point to yes.") {
+    return "positive";
+  }
+  else if (answer === "Reply hazy, try again." || answer === "Ask again later." || answer === "Better not tell you now." || answer === "Cannot predict now." || answer === "Concentrate and ask again.") {
+    return "negative";
+  }
+  else if (answer === "Don't count on it." || answer === "My reply is no." || answer === "My sources say no." || answer === "Outlook not so good." || answer === "Very doubtful.") {
+    return "very negative";
+  }
+
+  
 }
 
 /* 
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index a10cc9ac2..8a817bf5a 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 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..c5024a0fb 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,9 +1,12 @@
 // Add comments to explain what this function does. You're meant to use Google!
+//This function returns a random number between 0 (inclusive),  and 1 (exclusive):
 function getRandomNumber() {
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
+//This function concatenates two or more strings, and returns a new joined strings
+
 function combine2Words(word1, word2) {
   return word1.concat(word2);
 }
@@ -11,6 +14,8 @@ function combine2Words(word1, word2) {
 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 + " ".concat(secondWord) + " ".concat(thirdWord);
+
 }
 
 /* 
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..0cfa3674c 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,12 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
+
+function calculateSalesTax(price) {
+  var salesTax = price * 0.2;
+  salesPrice = price + salesTax;
+  return salesPrice;
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +22,9 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(price) {
+  return "£" + calculateSalesTax(price).toFixed(2);
+}
 
 /* 
 ===================================================