diff --git a/.prettierrc b/.prettierrc
new file mode 100644
index 000000000..1053b8fe2
--- /dev/null
+++ b/.prettierrc
@@ -0,0 +1,6 @@
+{
+  "singleQuote": true,
+  "tabWidth": 2,
+  "trailingComma": "none",
+  "printWidth": 100
+}
diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..8073ba0a9 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1 @@
-console.log("Hello world");
+console.log("Hello world I'm learning JavaScript");
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..ec3442dee 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `greeting`
-
+const 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..137ad6b84 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,3 @@
 // Start by creating a variable `message`
-
+const message = `Current Month January\n ${typeof "Current Month January"}`;
 console.log(message);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..275f812bb 100644
--- a/exercises/E-strings-concatenation/exercise.js
+++ b/exercises/E-strings-concatenation/exercise.js
@@ -1,3 +1,3 @@
 // Start by creating a variable `message`
-
+const message = "Hello, my name is " + "Junior";
 console.log(message);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..33056167b 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`
-
+const message = `My name is Junior and my name is ${
+  "Junior".length
+} characters long`;
 console.log(message);
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..4431c74a1 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,6 @@
 const name = " Daniel  ";
+const message = `My name is ${name.trim()} and 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..0d9b65fca 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,9 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+const numberOfStudents = 25;
+const numberOfMentors = 25;
+
+console.log(`Total number of students: ${numberOfStudents}`);
+console.log(`Totla number of mentors; ${numberOfMentors}`);
+console.log(
+  `Total number of students and mentors: ${numberOfStudents + numberOfMentors}`
+);
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..54daa298f 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,12 @@
-var numberOfStudents = 15;
-var numberOfMentors = 8;
+const numberOfStudents = 15;
+const numberOfMentors = 8;
+
+//Getting the total number of people either students or mentors
+const totalNumberOfPeople = numberOfMentors + numberOfStudents;
+
+//Getting the percentage of mentors and students
+const studentPercentage = (numberOfStudents / totalNumberOfPeople) * 100;
+const mentorPercentage = (numberOfMentors / totalNumberOfPeople) * 100;
+
+console.log(`Percentage students: ${Math.round(studentPercentage)}%`);
+console.log(`Percentage mentors: ${Math.round(mentorPercentage)}%`);
diff --git a/exercises/J-functions/README.md b/exercises/J-functions/README.md
index a5c765cef..22105ca2a 100644
--- a/exercises/J-functions/README.md
+++ b/exercises/J-functions/README.md
@@ -20,8 +20,8 @@ console.log(result); // 4
 
 ## Exercise
 
-* Complete the function in exercise.js so that it halves the input
-* Try calling the function more than once with some different numbers
+- Complete the function in exercise.js so that it halves the input
+- Try calling the function more than once with some different numbers
 
 > Remember to use the return keyword to get a value out of the function
 
@@ -33,7 +33,7 @@ console.log(result); // 4
 
 ## Exercise 2
 
-* Complete the function in exercise2.js so that it triples the input
+- Complete the function in exercise2.js so that it triples the input
 
 ## Expected result
 
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..e523dc9ea 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,5 +1,7 @@
 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..1949bb03f 100644
--- a/exercises/J-functions/exercise2.js
+++ b/exercises/J-functions/exercise2.js
@@ -1,5 +1,7 @@
 function triple(number) {
   // complete function here
+
+  return number * 3;
 }
 
 var result = triple(12);
diff --git a/exercises/K-functions-parameters/README.md b/exercises/K-functions-parameters/README.md
index 02ab2a844..1614e221b 100644
--- a/exercises/K-functions-parameters/README.md
+++ b/exercises/K-functions-parameters/README.md
@@ -20,7 +20,7 @@ function add(num1, num2) {
 
 ## Exercise
 
-* Write a function that multiplies two numbers together
+- Write a function that multiplies two numbers together
 
 ## Expected result
 
@@ -30,7 +30,7 @@ function add(num1, num2) {
 
 ## Exercise 2
 
-* From scratch, write a function that divides two numbers
+- From scratch, write a function that divides two numbers
 
 ## Expected result
 
@@ -40,7 +40,7 @@ function add(num1, num2) {
 
 ## Exercise 3
 
-* Write a function that takes a name (a string) and returns a greeting
+- Write a function that takes a name (a string) and returns a greeting
 
 ## Expected result
 
@@ -50,8 +50,8 @@ Hello, my name is Daniel
 
 ## Exercise 4
 
-* Write a function that adds two numbers together
-* Call the function, passing `13` and `124` as parameters, and assigning the returned value to a variable `sum`
+- Write a function that adds two numbers together
+- Call the function, passing `13` and `124` as parameters, and assigning the returned value to a variable `sum`
 
 ## Expected result
 
@@ -61,7 +61,7 @@ Hello, my name is Daniel
 
 ## Exercise 5
 
-* Write a function that takes a name (a string) and an age (a number) and returns a greeting (a string)
+- Write a function that takes a name (a string) and an age (a number) and returns a greeting (a string)
 
 ## Expected result
 
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..4fb1a0382 100644
--- a/exercises/K-functions-parameters/exercise.js
+++ b/exercises/K-functions-parameters/exercise.js
@@ -1,6 +1,8 @@
 // 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..a6caeea94 100644
--- a/exercises/K-functions-parameters/exercise2.js
+++ b/exercises/K-functions-parameters/exercise2.js
@@ -1,5 +1,8 @@
 // Declare your function first
+const divide = (num1, num2) => {
+  return num1 / num2;
+};
 
-var result = divide(3, 4);
+const 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..03a7a75db 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,5 +1,8 @@
 // Write your function here
+const createGreeting = (name) => {
+  return `Hello, my name is ${name}`;
+};
 
-var greeting = createGreeting("Daniel");
+const greeting = createGreeting("Daniel");
 
 console.log(greeting);
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..cd8aadc36 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,9 @@
 // Declare your function first
+const Add = (num1, num2) => {
+  return num1 + num2;
+};
 
 // Call the function and assign to a variable `sum`
+const 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..b00575249 100644
--- a/exercises/K-functions-parameters/exercise5.js
+++ b/exercises/K-functions-parameters/exercise5.js
@@ -1,4 +1,7 @@
 // Declare your function here
+const 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..faba97154 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -1,5 +1,17 @@
-var mentor1 = "Daniel";
-var mentor2 = "Irina";
-var mentor3 = "Mimi";
-var mentor4 = "Rob";
-var mentor5 = "Yohannes";
+const numberOfStudents = 15;
+const numberOfMentors = 20;
+const totalNumberOfPeople = numberOfMentors + numberOfStudents;
+
+const GetPercentage = (number_to_get_ratio) => {
+  return (number_to_get_ratio / totalNumberOfPeople) * 100;
+};
+
+const DisplayPercentage = () => {
+  const studentPercentage = Math.round(GetPercentage(numberOfStudents));
+  const mentorPercentage = Math.round(GetPercentage(numberOfMentors));
+
+  console.log(`Percentage students: ${studentPercentage}%`);
+  console.log(`Percentage mentors: ${mentorPercentage}%`);
+};
+
+DisplayPercentage();
diff --git a/exercises/L-functions-nested/exercise2.js b/exercises/L-functions-nested/exercise2.js
new file mode 100644
index 000000000..4ec3e57fa
--- /dev/null
+++ b/exercises/L-functions-nested/exercise2.js
@@ -0,0 +1,11 @@
+const mentor1 = "Daniel";
+const mentor2 = "Irina";
+const mentor3 = "Mimi";
+const mentor4 = "Rob";
+const mentor5 = "Yohannes";
+
+console.log(mentor1);
+console.log(mentor2);
+console.log(mentor3);
+console.log(mentor4);
+console.log(mentor5);
diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index 70a2fe863..21c8b4855 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(amount) {
+  return amount * 1.4;
+}
 
 /*
   CURRENCY FORMATTING
@@ -15,7 +17,10 @@ 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(amount) {
+  const percentageAmountToConvert = amount - (1 / 100) * amount;
+  return 5.7 * percentageAmountToConvert;
+}
 
 /* ======= 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 067dd0f5b..9463af8b6 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,26 +16,32 @@
   the final result to the variable goodCode
 */
 
-function add() {
+function add(num1, num2) {
+    return num1 + num2;
+}   
 
+function multiply(num1, num2) {
+    return num1 * num2
 }
 
-function multiply() {
-
-}
-
-function format() {
-
+function format(num) {
+    return `£${num}`
 }
 
 const startingValue = 2
 
 // Why can this code be seen as bad practice? Comment your answer.
-let badCode = 
 
-/* BETTER PRACTICE */
+/**
+ * Chaining of this methods all in one line is unclear on what is happening at first glance
+ * Prone to making errors while chaining this methods 
+**/
+let badCode = format(multiply(add(startingValue, 10), 2))
 
-let goodCode = 
+/* BETTER PRACTICE */
+const sum = add(startingValue, 10);
+const multipleOfSum = multiply(sum,2)
+let goodCode = format(multipleOfSum)
 
 /* ======= 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 e32182cfe..7d234382f 100644
--- a/extra/3-magic-8-ball.js
+++ b/extra/3-magic-8-ball.js
@@ -47,6 +47,38 @@
 // and return the answer.
 function shakeBall() {
   //Write your code in here
+
+  const possibleAnswers = [
+    '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.'
+  ];
+
+  console.log('The ball has shaken!');
+
+  const possibleAnswerIndex = Math.floor(Math.random() * 20);
+
+  return possibleAnswers[possibleAnswerIndex];
 }
 
 /* 
@@ -60,6 +92,60 @@ function shakeBall() {
 */
 function checkAnswer(answer) {
   //Write your code in here
+
+  const possibleAnswers = [
+    {
+      veryPositive: [
+        'It is certain.',
+        'It is decidedly so.',
+        'Without a doubt.',
+        'Yes - definitely.',
+        'You may rely on it.'
+      ],
+      positive: [
+        'As I see it, yes.',
+        'Most likely.',
+        'Outlook good.',
+        'Yes.',
+        'Signs point to yes.'
+      ],
+
+      negative: [
+        'Reply hazy, try again.',
+        'Ask again later.',
+        'Better not tell you now.',
+        'Cannot predict now.',
+        'Concentrate and ask again.'
+      ],
+
+      veryNegative: [
+        "Don't count on it.",
+        'My reply is no.',
+        'My sources say no.',
+        'Outlook not so good.'
+      ]
+    }
+  ];
+
+  let status = '';
+  possibleAnswers.forEach((array) => {
+    if (array.veryPositive.includes(answer)) {
+      status = 'very positive';
+    }
+
+    if (array.positive.includes(answer)) {
+      status = 'positive';
+    }
+
+    if (array.negative.includes(answer)) {
+      status = 'negative';
+    }
+
+    if (array.veryNegative.includes(answer)) {
+      status = 'very negative';
+    }
+  });
+  return status;
 }
 
 /* 
@@ -82,9 +168,9 @@ console.log = function () {
 function test(test_name, expr) {
   let status;
   if (expr) {
-    status = "PASSED";
+    status = 'PASSED';
   } else {
-    status = "FAILED";
+    status = 'FAILED';
   }
 
   logged = undefined;
@@ -94,27 +180,22 @@ function test(test_name, expr) {
 const validAnswers = [];
 function testAll() {
   const answer = shakeBall();
-  test(
-    `shakeBall logs "The ball has shaken!"`,
-    logged === "The ball has shaken!"
-  );
-  test(`shakeBall returns an string answer`, typeof answer === "string");
+  test(`shakeBall logs "The ball has shaken!"`, logged === 'The ball has shaken!');
+  test(`shakeBall returns an string answer`, typeof answer === 'string');
 
   test(
     `checkAnswer("It is decidedly so.") returns "very positive`,
-    checkAnswer("It is decidedly so.") === "very positive"
+    checkAnswer('It is decidedly so.') === 'very positive'
   );
 
   test(
     `checkAnswer("My reply is no.") returns "very negative`,
-    checkAnswer("My reply is no.") === "very negative"
+    checkAnswer('My reply is no.') === 'very negative'
   );
 
   test(
     `checkAnswer returns the level of positivity"`,
-    ["very positive", "positive", "negative", "very negative"].includes(
-      checkAnswer(answer)
-    )
+    ['very positive', 'positive', 'negative', 'very negative'].includes(checkAnswer(answer))
   );
   const answers = new Set();
   for (let i = 0; i < 10; ++i) {
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index 0a21afd1b..0591e38d8 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) {
-    return 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;
+  const total = a + b;
 
-    return "The total is total"
+  return `The total is ${total}`;
 }
 
 /* 
@@ -24,19 +25,25 @@ To run these tests type `node 1-syntax-errors.js` into your terminal
 ===================================================
 */
 
-const util = require('util');
+const util = require("util");
 
 function test(test_name, actual, expected) {
-    let status;
-    if (actual === expected) {
-        status = "PASSED";
-    } else {
-        status = `FAILED: expected: ${util.inspect(expected)} but your function returned: ${util.inspect(actual)}`;
-    }
-
-    console.log(`${test_name}: ${status}`);
+  let status;
+  if (actual === expected) {
+    status = "PASSED";
+  } else {
+    status = `FAILED: expected: ${util.inspect(
+      expected
+    )} but your function returned: ${util.inspect(actual)}`;
+  }
+
+  console.log(`${test_name}: ${status}`);
 }
 
 test("fixed addNumbers function - case 1", addNumbers(3, 4, 6), 13);
-test("fixed introduceMe function", introduceMe("Sonjide", 27), "Hello, my name is Sonjide and I am 27 years old");
-test("fixed getTotal function", getTotal(23, 5), "The total is 28");
+test(
+  "fixed introduceMe function - case 2",
+  introduceMe("Sonjide", 27),
+  "Hello, my name is Sonjide and I am 27 years old"
+);
+test("fixed getTotal function - case 3", getTotal(23, 5), "The total is 28");
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..27067c28d 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,9 +1,22 @@
 // Add comments to explain what this function does. You're meant to use Google!
+/**
+
+  * @description Function returns a random floating numbers bounded from [0, 10)
+
+ **/
 function getNumber() {
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
+
+/**
+ * @description Function concatenates 2 values together
+ * @param w1
+ * @param  w2
+ * @returns Joint result of @param w1 and @param w2
+ * @example w1='J' and w2='mac' result is 'Jmac'
+ **/
 function s(w1, w2) {
   return w1.concat(w2);
 }
@@ -11,6 +24,8 @@ 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..bb5fc6fb4 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,11 @@
   Sales tax is 20% of the price of the product
 */
 
-function calculateSalesTax() {}
+function calculateSalesTax(price) {
+  const chargeAmount = price + (20 / 100) * price;
+
+  return chargeAmount;
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +21,10 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(amount) {
+  const taxedAmount = calculateSalesTax(amount).toFixed(2);
+  return `£${taxedAmount}`;
+}
 
 /* 
 ===================================================