diff --git a/exercise.js b/exercise.js
new file mode 100644
index 000000000..99ac19117
--- /dev/null
+++ b/exercise.js
@@ -0,0 +1,120 @@
+/*function isEven (num)  {
+    if (num%2 === 0) 
+        return true;
+    else 
+        return false;
+
+}
+
+console.log(isEven(235))*/
+
+function isEven (num) {
+    
+}
+
+
+/*function moreThanSixGoal (num1, num2) {
+    let total =  num1 + num2;
+    if (total > 6) 
+        return true; 
+    else 
+        return false;        
+
+}
+
+console.log (moreThanSixGoal(2));
+console.log (moreThanSixGoal(8));*/
+
+/*
+function numberChecker(num) {
+    if (num > 20) {
+      return `${num} is greater than 20`;
+    } else if (num === 20) {
+      return `${num} is equal to 20`;
+    } else if (num < 20) {
+      return `${num} is less than 20`;
+    } else {
+      return `${num} isn't even a number :(`;
+    }
+  }
+  
+ console.log(numberChecker(10));
+ console.log(numberChecker(56));
+
+
+ function yourMood(message) {
+     if (message === "happy") {
+         return "Good job, you're doing great!";
+     } else if (message ==="sad") {
+        return "Every cloud has a silver lining";
+     } else if (typeof message === "number") {
+         return "Beep beep boop"
+     } else {
+         return "I'm sorry, I'm still learning about feelings!";
+     }
+ }
+
+ console.log(yourMood("happy"));
+ console.log(yourMood("sad"));
+ console.log (yourMood("sasdfasdf"));
+ */
+
+ /*let num = 10
+num > 5 && num < 15
+num < 10 || num === 10
+false || true
+!true
+let greaterThan5 = num > 5
+!greaterThan5
+!(num === 10)
+
+function checkUsername (userName, userType) {
+    if (userName[0] === userName[0].toUppercase()  &&  userName.length > 5 && userName < 10)  {
+        return "Username valid";
+    } else if (userType === "admin" || userType === "manager") {
+        return "Username valid";
+    } else {
+        return "Username invalid";
+    }
+       
+}
+
+console.log(checkUsername("Irina", "admin"));
+*/
+
+/*
+const fruits = ["banana", "apple", "strawberry", "kiwi", "fig", "orange"];
+console.log(fruits[2]);
+console.log(fruits[3]);
+console.log(fruits[5]);
+console.log(fruits[0]);
+console.log(fruits[-3]);
+console.log(fruits[8]);
+
+fruits[6] = "peach";
+
+console.log(fruits);
+
+fruits[10] = "pear"; 
+console.log(fruits);
+*/
+
+const products = ["smart phones", "chargers", "laptops", "monitors", "printers", "keyboards", "mice"]; 
+
+function numberOfProducts(products) {
+    return products.length; 
+}
+
+function inStock(myProducts, nameOfProduct) {
+    for (let i = 0; i < myProducts.length; i++) {
+        
+        if (nameOfProduct === myProducts[i]) {
+            return true
+    } else {
+        return false
+    } 
+    
+}
+}
+
+console.log(inStock(products, "mice"));
\ No newline at end of file
diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..31deceb06 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1,5 @@
 console.log("Hello world");
+
+
+
+console.log(12345);
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..2a811c6ec 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `message`
-
+let message = "This is a string";
 console.log(message);
+let messageType = typeof(message);
+console.log(messageType);
\ No newline at end of file
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..3dfd11dd7 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 myName = "Irina";
+let message = greetingStart + myName;
 
 console.log(message);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..ab34a19f7 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`
 
+let myName = "Irina";
+let nameLength = myName.length;
+let message = "Hello! My name is " + myName + " 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..1a11615ad 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,8 @@
 const name = " Daniel  ";
-
+let message = "My name is " + name + " and my name is 6 characters long."
 console.log(message);
+let nameTrim = name.trim();
+
+let message2 = "My name is " + nameTrim + " and my name is 6 characters long";
+console.log(message2);
+
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..cf243a47f 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,8 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+let numberOfStudents = 8;
+let numberOfMentors = 15;
+let totalNumber = numberOfMentors + numberOfStudents;
+
+console.log("Number of students: " + numberOfStudents);
+console.log("Number of mentors: " + numberOfMentors); 
+console.log("Total number of students and mentors " + totalNumber);
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..99aa50c4e 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,14 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+
+let totalNumber = numberOfMentors + numberOfStudents;
+
+let percentOfStudents = numberOfStudents * 100 / totalNumber; 
+let percentOfMentors = numberOfMentors * 100 / totalNumber;
+
+
+
+let roughPerSt = Math.round(percentOfStudents);
+let roughPerMent= Math.round(percentOfMentors);
+console.log("Percentage students: " + roughPerMent + "%");
+console.log("Percentage mentors: " + roughPerSt + "%");
\ No newline at end of file
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..8a48f807b 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,7 +1,10 @@
 function halve(number) {
   // complete the function here
+  return number / 2;
 }
 
 var result = halve(12);
 
 console.log(result);
+console.log(halve(6));
+
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..0b0d803b1 100644
--- a/exercises/J-functions/exercise2.js
+++ b/exercises/J-functions/exercise2.js
@@ -1,7 +1,9 @@
 function triple(number) {
   // complete function here
+  return number*3;
 }
 
 var result = triple(12);
 
 console.log(result);
+console.log(triple(5));
\ No newline at end of file
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..cb0b0d927 100644
--- a/exercises/K-functions-parameters/exercise.js
+++ b/exercises/K-functions-parameters/exercise.js
@@ -1,5 +1,6 @@
 // Complete the function so that it takes input parameters
-function multiply() {
+function multiply(num1, num2) {
+  return num1 * num2;
   // Calculate the result of the function and return it
 }
 
diff --git a/exercises/K-functions-parameters/exercise2.js b/exercises/K-functions-parameters/exercise2.js
index db7a8904b..02a698a36 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(a, b) {
+    return a/b;
+}
 
 var result = divide(3, 4);
 
diff --git a/exercises/K-functions-parameters/exercise3.js b/exercises/K-functions-parameters/exercise3.js
index 537e9f4ec..075215630 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(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..ae7a5dd6f 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,7 @@
 // Declare your function first
-
+function sumNumbers (a, b) {
+    return a+b;
+}
 // Call the function and assign to a variable `sum`
-
+var sum = sumNumbers (13, 124);
 console.log(sum);
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..96a112234 100644
--- a/exercises/K-functions-parameters/exercise5.js
+++ b/exercises/K-functions-parameters/exercise5.js
@@ -1,4 +1,9 @@
 // Declare your function here
+function createLongGreeting(name, age) {
+    return "Hello! My name is " + name + " and I am " + 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..0ce3e66ea 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -3,3 +3,14 @@ var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+
+
+function greeting(name) {
+    let sayHello = "hello " + name;
+    return sayHello.toUpperCase();
+}
+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..dd3237e3f 100644
--- a/extra/1-currency-conversion.js
+++ b/extra/1-currency-conversion.js
@@ -5,7 +5,11 @@
   Write a function that converts a price to USD (exchange rate is 1.4 $ to £)
 */
 
-function convertToUSD() {}
+function convertToUSD(oldPrice) {
+  return oldPrice * 1.4;
+}
+
+
 
 /*
   CURRENCY CONVERSION
@@ -15,7 +19,10 @@ 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(price) {
+  let newPrice = ((price * 99) / 100) * 5.7;
+  let brazilPrice = newPrice.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..575d5e785 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(a, b) {
+  return a+b;
 }
 
-function multiply() {
-
+function multiply(a, b) {
+  return a*b;
 }
 
-function format() {
-
+function format(a) {
+  return "£"+a; 
 }
 
 const startingValue = 2;
 
 // Why can this code be seen as bad practice? Comment your answer.
-let badCode =
+// too many functions, difficult to understand;
+format (multiply(add(startingValue, 10), 2));
+
 
 /* BETTER PRACTICE */
 
-let goodCode =
+let sum = add(startingValue, 10);
+let mult = multiply(sum, 2);
+
+
+let goodCode = format(mult);
 
 /* ======= 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..7172d4a58 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,16 +1,18 @@
 // 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;
+ let 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..905f49320 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,14 +1,21 @@
 // Add comments to explain what this function does. You're meant to use Google!
+
+/* The Math.random() method returns a random number from 0 (inclusive) up to but not including 1 (exclusive). In this case the function will  return a random number between 1 and 10: */
 function getRandomNumber() {
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
+
+/* The concat() method joins two or more strings. And at the same time we don't change the existing string. */
 function combine2Words(word1, word2) {
   return word1.concat(word2);
 }
 
 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..d37922302 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,14 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
+function calculateSalesTax(num) {
+  let tax = (num * 20) / 100;
+  return tax + num;
+}
+
+
+
+
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +24,9 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(num) {
+  return "£" + calculateSalesTax(num).toFixed(2);
+}
 
 /* 
 ===================================================
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"
+        ]
       }
     ]
   },