diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..eafaaf8b9 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1,4 @@
-console.log("Hello world");
+console.log("hello world. give me your positive energy I need it to complete this course!");
+
+console.log(7);
+console.log('I will make it');
\ No newline at end of file
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..f3369a672 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `greeting`
-
+var greeting = "hi Im elahe"
+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..52a92b5b2 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 = "anyone can help me with terminal?"
+var messagetype = typeof message;
 console.log(message);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..5f0917989 100644
--- a/exercises/E-strings-concatenation/exercise.js
+++ b/exercises/E-strings-concatenation/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `message`
-
+var greetingStart = "Hello, my name is ";
+var name = "elahe";
+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..34b7c362a 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `message`
+var name = "Elahe";
+var nameLength = name.length;
 
-console.log(message);
+console.log(nameLength);
+console.log()
\ No newline at end of file
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..4f7fba06a 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,14 @@
-const name = " Daniel  ";
+var name = "  Elahe";
+var nameLength = name.length;
+console.log(nameLength);
+
+let newString = (`my name is ${name} which includes ${nameLength} characters`);
+console.log(newString);
+
+
+console.log(newString.trim()); 
+// why trim is not working here?
+
+console.log(name.trim());
+
 
-console.log(message);
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..81934385c 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,4 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+let numberOfStudents = 70;
+let numberOfTeachers = 20;
+console.log(numberOfStudents+numberOfTeachers);
\ No newline at end of file
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..7af2d3dd8 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,14 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+var total = (numberOfStudents+numberOfMentors);
+console.log(total);
+
+let x = (numberOfStudents/total*100);
+console.log(x);
+
+let y = (numberOfMentors/total*100);
+console.log(y);
+
+console.log(Math.round(x));
+console.log(Math.round(y));
+
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..f31b85e40 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,7 +1,16 @@
 function halve(number) {
-  // complete the function here
+  return number/2;
 }
 
 var result = halve(12);
 
 console.log(result);
+
+var result = halve(20);
+console.log(result);
+
+var result = halve(87);
+console.log(result);
+console.log(Math.round(result));
+
+
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..a57a8d69a 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*3;
 }
 
 var result = triple(12);
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..2ae706109 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..f117d7bd1 100644
--- a/exercises/K-functions-parameters/exercise2.js
+++ b/exercises/K-functions-parameters/exercise2.js
@@ -1,4 +1,6 @@
-// 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..e5bbfb303 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,5 +1,7 @@
 // Write your function here
-
+function createGreeting(name){
+    return 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..bb5e8a8d6 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,7 @@
 // Declare your function first
 
 // Call the function and assign to a variable `sum`
-
-console.log(sum);
+function sum(num1, num2){
+    return num1+num2;
+}
+console.log(sum(13, 124));
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..fd2858b95 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(name, age){
+    return (`i am ${name} and i am ${age} year old`)
+}
 
 const greeting = createLongGreeting("Daniel", 30);
 
diff --git a/exercises/L-functions-nested/exercise.js b/exercises/L-functions-nested/exercise.js
index a5d377442..860547cfc 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -1,5 +1,18 @@
-var mentor1 = "Daniel";
-var mentor2 = "Irina";
-var mentor3 = "Mimi";
-var mentor4 = "Rob";
-var mentor5 = "Yohannes";
+function greeting(name){
+    
+    return(`HELLO ${name}`);
+
+}
+console.log(greeting("daniel").toUpperCase());
+console.log(greeting("irina").toUpperCase());
+console.log(greeting("mimi").toUpperCase());
+console.log(greeting("rob").toUpperCase());
+console.log(greeting("yohannes").toUpperCase());
+
+
+
+let mentor1 = "Daniel";
+let mentor2 = "Irina";
+let mentor3 = "Mimi";
+let mentor4 = "Rob";
+let mentor5 = "Yohannes";
diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index 75b3c6aab..30012a094 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(num) {
+  return num * 1.4
+}
 
 /*
   CURRENCY CONVERSION
@@ -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(num) {
+  return Number(((num * 0.99) * 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 b4f8c4c1b..b993541a9 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,26 +16,27 @@
   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));
+//  badcode as it's a bit complicated to read
 
 /* BETTER PRACTICE */
 
-let goodCode =
+let goodCode = (format(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/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index a10cc9ac2..41fd2db11 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,18 +1,28 @@
 // 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";
 }
 
+
 /* 
 ===================================================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
diff --git a/mandatory/2-logic-error.js b/mandatory/2-logic-error.js
index 9cca7603b..17f704886 100644
--- a/mandatory/2-logic-error.js
+++ b/mandatory/2-logic-error.js
@@ -1,18 +1,26 @@
 // 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;
+  let result = a * b * c;
+ return result;
 }
 
+  
+
+
 /* 
 ===================================================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
diff --git a/mandatory/3-function-output.js b/mandatory/3-function-output.js
index 5a953ba60..c9724dd77 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -2,16 +2,21 @@
 function getRandomNumber() {
   return Math.random() * 10;
 }
+// MATH.RANDOM : to find a random number between 0 to 1. so tofind a number between 0 to 100 we need to multiple it to 100.
 
 // Add comments to explain what this function does. You're meant to use Google!
 function combine2Words(word1, word2) {
   return word1.concat(word2);
-}
+} 
+// CONCAT: to mix arrays together we can use concat. the other way is spread operator.
 
 function concatenate(firstWord, secondWord, thirdWord) {
+  return `${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.
-}
+
 
 /* 
 ===================================================
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..a7084c4d7 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,10 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
+function calculateSalesTax(num) {
+ return num * 1.2;
+
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +20,16 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(num) {
+  let final = ((num * 1.2).toFixed(2)).toString();
+  return `£${final}`;
+  
+}
+
+  //  function completed        
+
+
+
 
 /* 
 ===================================================
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"
+        ]
       }
     ]
   },