diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..7decc441e 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `greeting`
+let 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..0bb9b8b7f 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,7 @@
 // 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..22eef8e4d 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 = "Aaron";
+
+var message = greetingStart + name;
 
 console.log(message);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..b53ff794f 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,7 @@
 // Start by creating a variable `message`
+var name = "Aaron";
+var nameLength = name.length;
+
+var message = `My name is ${name} my name is ${nameLength} characters long`;
 
 console.log(message);
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..08fa54972 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,5 @@
 const name = " Daniel  ";
 
+var message = `My name is ${name.trim()} and my name is ${name.trim().length} characters long`
+
 console.log(message);
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..8799b662d 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,7 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+const numberOfStudents = 15;
+const numberOfMentors = 8;
+
+console.log("Number of students: " + numberOfStudents);
+console.log("Number of Mentors: " + numberOfMentors);
+console.log("Total number of students and mentors: " + (numberOfMentors + numberOfStudents));
\ No newline at end of file
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..323277586 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,5 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+
+console.log("Percentage of students: " + (Math.round(numberOfStudents * 100 / (numberOfStudents + numberOfMentors))) + '%');
+console.log("Percentage of mentors: " + (Math.round(numberOfMentors * 100 / (numberOfStudents + numberOfMentors))) + '%');
\ 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..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..4805ef7dc 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(num1, num2) {
+    return num1 / num2;
+}
 
 var result = divide(3, 4);
 
diff --git a/exercises/K-functions-parameters/exercise3.js b/exercises/K-functions-parameters/exercise3.js
index 537e9f4ec..c229f5f4c 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(name1) {
+    return "Hello, my name is " + name1;
+}
 
 var greeting = createGreeting("Daniel");
 
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..0ddef467b 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,10 @@
 // Declare your function first
+function addNumbers(num1, num2) {
+    return num1 + num2;
+}
 
 // Call the function and assign to a variable `sum`
 
+sum = addNumbers(13, 124);
+
 console.log(sum);
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..869e16b07 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(name1, age) {
+    return `Hello, my name is ${name1} 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..2ba6d7e70 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -3,3 +3,17 @@ var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+
+function shoutyGreeting(uName) {
+    return "HELLO " + upperName(uName);
+}
+
+function upperName(uName) {
+    return uName.toUpperCase();
+}
+
+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..2abefe729 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(priceInGBP) {
+  return priceInGBP * 1.4;
+}
 
 /*
   CURRENCY CONVERSION
@@ -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(priceInGBP) {
+  return Math.round(((priceInGBP - (priceInGBP / 100)) * 5.7) * 100) / 100;
+}
 
 /* ======= 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..aad668d08 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,26 +16,28 @@
   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(num) {
+  return "£" + num;
 }
 
 const startingValue = 2;
 
 // Why can this code be seen as bad practice? Comment your answer.
-let badCode =
+let badCode = format(multiply(add(startingValue, 10), 2));
+
+//this code could be seen as bad practice because it isn't easy to read what is happening.
 
 /* BETTER PRACTICE */
 
-let goodCode =
+let goodCode = "£" + ((startingValue + 10) * 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/3-magic-8-ball.js b/extra/3-magic-8-ball.js
index f3adbefa5..4fc4dda9b 100644
--- a/extra/3-magic-8-ball.js
+++ b/extra/3-magic-8-ball.js
@@ -43,10 +43,38 @@
     Very doubtful.
 */
 
+  var responses = [
+    "It is certain.",
+    "It is decidedly so.",
+    "Without a doubt.",
+    "Yes - definitely.",
+    "You may rely on it.",
+
+    "As I see it, yes.",
+    "Most likely.",
+    "Outlook good.",
+    "Yes.",
+    "Signs point to yes.",
+
+    "Reply hazy, try again.",
+    "Ask again later.",
+    "Better not tell you now.",
+    "Cannot predict now.",
+    "Concentrate and ask again.",
+
+    "Don't count on it.",
+    "My reply is no.",
+    "My sources say no.",
+    "Outlook not so good.",
+    "Very doubtful.",
+  ];
+
 // This should log "The ball has shaken!"
 // and return the answer.
 function shakeBall() {
   //Write your code in here
+  console.log("The ball has shaken!");
+  return responses[Math.floor(Math.random() * responses.length)];
 }
 
 /* 
@@ -60,6 +88,24 @@ function shakeBall() {
 */
 function checkAnswer(answer) {
   //Write your code in here
+  let answerIndex = responses.indexOf(answer);
+
+  if(answerIndex <= 5) {
+    return "very positive";
+  } 
+  else if(answerIndex <= 10) {
+    return "positive";
+  }
+  else if(answerIndex <= 15) {
+    return "negative";
+  }
+  else if(answerIndex <= 20) {
+    return "very negative";
+  }
+  else {
+    return "not a correct response"
+  }
+
 }
 
 /* 
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index a10cc9ac2..98360ac6b 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..4f46b6c2b 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,16 +1,20 @@
 // Add comments to explain what this function does. You're meant to use Google!
 function getRandomNumber() {
+  // Math.random() returns a number between 0 and 1 then using * 10 makes it return between 0 and 10 
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
 function combine2Words(word1, word2) {
+  // concat is returning the contents of word2 added onto the end of the contents of word1 and the result is them being combined.
+  // it does not change the original contents of word1 only returning the result
   return word1.concat(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, " ", thirdWord);
 }
 
 /* 
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..cb2e8beb9 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(preTaxPrice) {
+  return preTaxPrice *= 1.2;
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +19,9 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(preTaxPrice) {
+  return "£" + calculateSalesTax(preTaxPrice).toFixed(2);
+}
 
 /* 
 ===================================================