diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..dfbf46c18 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1,3 @@
-console.log("Hello world");
+console.log("Hello world, I started learning Javascript");
+console.log("Jello world");
+console.log(10);
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..ef7e25bb9 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,6 @@
 // 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..e677c1e43 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,17 @@
 // Start by creating a variable `message`
+// const message = "this is a string."
+//const messageType = typeof message
+
+
+const message = "this is a string.";
+const messageType = typeof message;
 
 console.log(message);
+console.log(messageType);
+
+
+const message1 = 56;
+const messageType1 = typeof message1;
+
+console.log(message1);
+console.log(messageType1);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..9d1bb6a99 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`
+const greetingStart = "Hello, my name is ";
+const myName =  "Zaw Khing.";
 
-console.log(message);
+const greeting = greetingStart + myName ;
+
+console.log(greeting);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..847d3e27f 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,8 @@
-// Start by creating a variable `message`
+const name = "Zaw Khing"
+const nameLength = name.length;// Start by creating a variable `message`
+
+//const myName = "My name is " + name + " and my name is " + nameLength + " characters long.";
+//console.log (myName);
+
+console.log("My name is " + name + " and 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..81a3a79b8 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,8 @@
-const name = " Daniel  ";
+//const name = " Daniel  ";
+const name = "     Zaw Myo Khing                    ";
+const nameTrimMethod = name.trim();
+const nameLength = name.length;
 
-console.log(message);
+const myName = `My name is ${nameTrimMethod} and my name is ${nameLength} characters long.`
+
+console.log(myName);
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..37a6ac6fe 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,11 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+
+const numberOfStudents = 50;
+const numberOfMentors = 10;
+
+const totalPeople = numberOfStudents + numberOfMentors;
+
+console.log("Number of students: " + numberOfStudents);
+console.log("Number of mentors: " + numberOfMentors);
+console.log("Total number of students and mentors: " + totalPeople);
+
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..fb7aa7aec 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,14 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+var sum = numberOfStudents + numberOfMentors;
+
+var percentageStudents = (numberOfStudents / sum) * 100;
+var students = Math.round(percentageStudents);
+
+var percentageMentors = (numberOfMentors / sum) * 100;
+var mentors = Math.round(percentageMentors);
+
+
+console.log(`Percentage students: ${students}%`);
+console.log(`Percentage mentors: ${mentors}%`);
+
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..7fc58d969 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,7 +1,12 @@
 function halve(number) {
   // complete the function here
+  return number / 2;
 }
 
 var result = halve(12);
+var result1 = halve(23);
+var result2 = halve(56);
 
 console.log(result);
+console.log(result1);
+console.log(result2);
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..c80aed200 100644
--- a/exercises/J-functions/exercise2.js
+++ b/exercises/J-functions/exercise2.js
@@ -1,7 +1,12 @@
 function triple(number) {
   // complete function here
+  return number * 3;
 }
 
 var result = triple(12);
+var result1 = triple(1234);
+var result2 = triple(0.2);
 
 console.log(result);
+console.log(result1);
+console.log(result2);
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..24789172a 100644
--- a/exercises/K-functions-parameters/exercise.js
+++ b/exercises/K-functions-parameters/exercise.js
@@ -1,9 +1,9 @@
 // Complete the function so that it takes input parameters
-function multiply() {
-  // Calculate the result of the function and return it
+function multiply(num1, num2) {
+   return num1 * num2; // Calculate the result of the function and return it
 }
 
 // Assign the result of calling the function the variable `result`
-var result = multiply(3, 4);
+const result = multiply(3, 4);
 
 console.log(result);
diff --git a/exercises/K-functions-parameters/exercise2.js b/exercises/K-functions-parameters/exercise2.js
index db7a8904b..91ddf23d8 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(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..ff7d1f7cc 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);
+//console.log(`Hello, My name is ${greeting}`);
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..4414cba8f 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,11 @@
 // Declare your function first
-
+function addTwoNumbers(num1, num2){
+  //sum = num1 + num2;
+  return num1 + num2;
+}
 // Call the function and assign to a variable `sum`
+ var sum = addTwoNumbers(13,124);
+ //var sum = addTwoNumbers(15,1234);
 
 console.log(sum);
+//console.log((addTwoNumbers)(132,124));
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..28922d139 100644
--- a/exercises/K-functions-parameters/exercise5.js
+++ b/exercises/K-functions-parameters/exercise5.js
@@ -1,5 +1,11 @@
 // Declare your function here
+function createGreeting(name, age){
 
-const greeting = createLongGreeting("Daniel", 30);
+    return `Hello, My name is ${name} and I'm ${age} years old`;
+}
 
+const greeting = createGreeting("Daniel", 30);
+//createLongGreeting();
+
+//(createLongGreeting)(`Hello, My name is ${greeting} and I'm ${greeting} years old`));
 console.log(greeting);
diff --git a/exercises/L-functions-nested/exercise.js b/exercises/L-functions-nested/exercise.js
index a5d377442..6a336bb22 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -3,3 +3,20 @@ var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+
+
+function getUpperCase(name){
+    return name.toUpperCase();
+}
+
+function greeting(name){
+   nameInUpperCase = getUpperCase(name);
+   const message = "Hello " + nameInUpperCase;
+   return message;
+}
+
+console.log(greeting(mentor1));
+console.log(greeting(mentor2));
+console.log(greeting(mentor3));
+console.log(greeting(mentor4));
+console.log(greeting(mentor5));
\ No newline at end of file
diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index 75b3c6aab..d582f4a57 100644
--- a/extra/1-currency-conversion.js
+++ b/extra/1-currency-conversion.js
@@ -5,7 +5,15 @@
   Write a function that converts a price to USD (exchange rate is 1.4 $ to £)
 */
 
-function convertToUSD() {}
+function convertToUSD(currency) {
+  return currency * 1.4;
+}
+
+const usDollar = convertToUSD(100);
+
+console.log(usDollar);
+
+
 
 /*
   CURRENCY CONVERSION
@@ -15,7 +23,15 @@ 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(currency) {
+  const convertIncludingFees = currency * 5.7 * 0.99;
+  currencyInTwoDecimal = Number(convertIncludingFees.toFixed(2));
+  return currencyInTwoDecimal;
+
+}
+//const brazillianDollar = convertToBRL(100);
+
+console.log(convertToBRL(100));
 
 /* ======= TESTS - DO NOT MODIFY ===== 
 There are some Tests in this file that will help you work out if your code is working.
@@ -39,3 +55,4 @@ test("convertToBRL function works for £30", () => {
 test("convertToBRL function works for £1.50", () => {
   expect(convertToBRL(1.5)).toEqual(8.46);
 });
+
diff --git a/extra/2-piping.js b/extra/2-piping.js
index b4f8c4c1b..c1589e264 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 result = num1 + num2;;
 }
 
-function multiply() {
-
+function multiply(num1, num2) {
+   return result = num1 * num2;
 }
 
-function format() {
-
+function format(num1) {
+    return result = "£" + num1;
 }
 
 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));
+
 
 /* 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/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index a10cc9ac2..178b9c928 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";
+  return `Hello, my name is ${name} and I am ${age} years old`;
+}
 
 function getTotal(a, b) {
-  total = a ++ b;
-
-  return "The total is total";
+  const total = a + b;
+  return "The total is " + total;
 }
 
 /* 
diff --git a/mandatory/2-logic-error.js b/mandatory/2-logic-error.js
index 9cca7603b..fddf6fdfb 100644
--- a/mandatory/2-logic-error.js
+++ b/mandatory/2-logic-error.js
@@ -1,16 +1,18 @@
 // The syntax for this function is valid but it has an error, find it and fix it.
 
 function trimWord(word) {
-  return wordtrim();
+  wordtrim = word.trim();
+  return wordtrim;
 }
 
 function getStringLength(word) {
-  return "word".length();
+  wordLength = word.length;
+  return wordLength;
 }
 
 function multiply(a, b, c) {
-  a * b * c;
-  return;
+  var sum = a * b * c;
+  return sum;
 }
 
 /* 
diff --git a/mandatory/3-function-output.js b/mandatory/3-function-output.js
index 5a953ba60..dd5b7f1b5 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,18 +1,21 @@
 // Add comments to explain what this function does. You're meant to use Google!
-function getRandomNumber() {
-  return Math.random() * 10;
+function getRandomNumber() {  //create function called getRandomNumber
+  return Math.random() * 10;  //returns a random number between 0 and 9
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
-function combine2Words(word1, word2) {
-  return word1.concat(word2);
+function combine2Words(word1, word2) {  //create function called combine2Words with 2 parameters
+  return word1.concat(word2);           //returns concat() method joins two strings.
 }
 
 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);
 }
-
+console.log(concatenate("code","your","future"));
+console.log(concatenate("I","like","icecream"));
+console.log(concatenate("I","am",19));
 /* 
 ===================================================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..6c46dbfbf 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,13 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
+function calculateSalesTax(productPrice) {
+  const salesTax = (productPrice / 100) * 20;
+  const totalPrice = productPrice + salesTax;
+  return totalPrice;
+}
+
+console.log(calculateSalesTax(123));
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +23,15 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(productPrice) {
+    const addTax = calculateSalesTax(productPrice);
+    const formatCurrency = addTax.toFixed(2);
+    return "£" + formatCurrency;
+}
+
+console.log(addTaxAndFormatCurrency(456));
+
+   
 
 /* 
 ===================================================
diff --git a/package.json b/package.json
index 93e0861e3..9e7f2ffeb 100644
--- a/package.json
+++ b/package.json
@@ -14,15 +14,21 @@
     "url": "https://github.com/CodeYourFuture/JavaScript-Core-1-Coursework-Week1/issues"
   },
   "jest": {
-    "setupFilesAfterEnv": ["jest-extended"],
+    "setupFilesAfterEnv": [
+      "jest-extended"
+    ],
     "projects": [
       {
         "displayName": "mandatory",
-        "testMatch": ["<rootDir>/mandatory/*.js"]
+        "testMatch": [
+          "<rootDir>/mandatory/*.js"
+        ]
       },
       {
         "displayName": "extra",
-        "testMatch": ["<rootDir>/extra/*.js"]
+        "testMatch": [
+          "<rootDir>/extra/*.js"
+        ]
       }
     ]
   },