diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 000000000..2404ad5a7
Binary files /dev/null and b/.DS_Store differ
diff --git a/exercises/.DS_Store b/exercises/.DS_Store
new file mode 100644
index 000000000..93f46191e
Binary files /dev/null and b/exercises/.DS_Store differ
diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..14fb99d7b 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1,2 @@
 console.log("Hello world");
+
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..9fd6c22e0 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,5 @@
 // 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..8263a1f1e 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `message`
-
-console.log(message);
+let greeting = "This is a string";
+let greetingType = typeof greeting;
+console.log(greeting);
+console.log(greetingType);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..30f38d093 100644
--- a/exercises/E-strings-concatenation/exercise.js
+++ b/exercises/E-strings-concatenation/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `message`
+let greetingStart = "Hello, my name is ";
+let name = "Saghar";
+let greeting = greetingStart + name;
 
-console.log(message);
+console.log(greeting);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..ee22172f2 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,9 @@
-// Start by creating a variable `message`
+let greetingStart = "Hello, my name is ";
+let firstName = "Saghar";
+let greeting = greetingStart + firstName;
+let nameLength = firstName.length;
 
-console.log(message);
+console.log(greeting + " and my name is " + nameLength + " characters long");
+
+// let nameLowerCase = firstName.toLowerCase();
+// console.log(nameLowerCase);
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..b73327e88 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,8 @@
 const name = " Daniel  ";
 
-console.log(message);
+let greetingStart = "Hello, my name is ";
+
+let greeting = greetingStart + name.trim();
+let nameLength = name.length;
+
+console.log(greeting + " and my name is " + nameLength + " characters long");
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..d181b262e 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,7 @@
-// Start by creating a variables `numberOfStudents` and `numberOfMentors`
+let numberOfStudents = 15;
+
+let numberOfMentors = 8;
+
+let total = numberOfStudents + numberOfMentors;
+
+console.log(total);
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..435cef410 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,7 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+let total = numberOfStudents + numberOfMentors;
+let studentPercentage = Math.round((numberOfStudents / total) * 100);
+let mentorPercentage = Math.round((numberOfMentors / total) * 100);
+console.log(studentPercentage + "%");
+console.log(mentorPercentage + "%");
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..e7278f7bd 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,5 +1,5 @@
 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..853ef62bd 100644
--- a/exercises/J-functions/exercise2.js
+++ b/exercises/J-functions/exercise2.js
@@ -1,5 +1,5 @@
 function triple(number) {
-  // complete function here
+  return number * 6;
 }
 
 var result = triple(12);
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..c15480416 100644
--- a/exercises/K-functions-parameters/exercise.js
+++ b/exercises/K-functions-parameters/exercise.js
@@ -1,6 +1,6 @@
 // Complete the function so that it takes input parameters
-function multiply() {
-  // Calculate the result of the function and return it
+function multiply(a, b) {
+  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..158155740 100644
--- a/exercises/K-functions-parameters/exercise2.js
+++ b/exercises/K-functions-parameters/exercise2.js
@@ -1,5 +1,8 @@
 // Declare your function first
+function divide(cat, dog) {
+  return cat / dog;
+}
 
-var result = divide(3, 4);
+var result = divide(4, 2);
 
 console.log(result);
diff --git a/exercises/K-functions-parameters/exercise3.js b/exercises/K-functions-parameters/exercise3.js
index 537e9f4ec..bed59804f 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,4 +1,6 @@
-// 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..23a16d416 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,8 @@
 // Declare your function first
 
 // Call the function and assign to a variable `sum`
+function sum(a, b) {
+  return a + b;
+}
 
-console.log(sum);
+console.log(sum(13, 124));
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..3d3daa97a 100644
--- a/exercises/K-functions-parameters/exercise5.js
+++ b/exercises/K-functions-parameters/exercise5.js
@@ -1,5 +1,8 @@
 // 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..cf883e471 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -3,3 +3,23 @@ var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+
+function upperCaseName(teacher) {
+  return teacher.toUpperCase();
+}
+
+// function shoutyGreeting(name) {
+//   console.log("HELLO " + name);
+// }
+
+// shoutyGreeting(mentor1);
+
+function shoutyGreeting(name) {
+  return "HELLO " + upperCaseName(name);
+}
+
+console.log(shoutyGreeting(mentor1));
+console.log(shoutyGreeting(mentor2));
+console.log(shoutyGreeting(mentor3));
+console.log(shoutyGreeting(mentor4));
+console.log(shoutyGreeting(mentor5));
diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index 75b3c6aab..07a9892b0 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(price) {
+  return price * 1.4;
+}
 
 /*
   CURRENCY CONVERSION
@@ -15,7 +17,12 @@ 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(price) {
+  let newPrice = (99 * price) / 100;
+  let convertedPrice = newPrice * 5.7;
+  let inStringPrice = convertedPrice.toFixed(2);
+  return parseFloat(inStringPrice);
+}
 
 /* ======= 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 b4f8c4c1b..f7b9c4547 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(numberOne, numberTwo) {
+  return numberOne + numberTwo;
 }
 
-function multiply() {
-
+function multiply(numberOne, numberTwo) {
+  return numberOne * numberTwo;
 }
 
-function format() {
-
+function format(formattedPrice) {
+  return "£" + formattedPrice;
 }
 
 const startingValue = 2;
 
 // Why can this code be seen as bad practice? Comment your answer.
-let badCode =
+// It is not clear and very confusing.
+let badCode = format(multiply(add(startingValue, 10), 2));
 
 /* BETTER PRACTICE */
-
-let goodCode =
+let addingNumber = add(startingValue, 10);
+let multiplyingNumber = multiply(addingNumber, 2);
+let formattingNumber = format(multiplyingNumber);
+let goodCode = formattingNumber;
 
 /* ======= 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 a10cc9ac2..7561cf3fb 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;
 }
+addNumbers(3, 4, 6);
 
-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;
 }
 
 /* 
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..eebf4abca 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!
+// Math.random() 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!
+// The concat() method is used to merge two or more arrays. This method does not change the existing arrays, but instead returns a new array.
 function combine2Words(word1, word2) {
   return word1.concat(word2);
 }
@@ -11,6 +13,7 @@ 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, " ", thirdWord);
 }
 
 /* 
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..9eef658fb 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) {
+  return price * 1.2;
+}
+
+// let totalWithTax = calculateSalesTax();
 
 /*
   CURRENCY FORMATTING
@@ -17,10 +21,12 @@ 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);
+}
 
 /* 
-===================================================
+====================`===============================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
 
 There are some Tests in this file that will help you work out if your code is working.