diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 000000000..b408795c6
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..c16147628
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..b0ea518e1 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1 @@
-console.log("Hello world");
+console.log(555);
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..5167ee198 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `greeting`
-
+var 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..5c087ec48 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,8 @@
 // Start by creating a variable `message`
+// var message = "This is a string";
+// var messageType = typeof message;
 
-console.log(message);
+// console.log(messageType);
+
+var message = "Terminal still scares me";
+console.log(typeof message);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..9c8a81b55 100644
--- a/exercises/E-strings-concatenation/exercise.js
+++ b/exercises/E-strings-concatenation/exercise.js
@@ -1,3 +1,8 @@
 // Start by creating a variable `message`
+var message = "Hello, my name is ";
+var firstName = "Gulnihal";
 
-console.log(message);
+var greeting = message + firstName;
+
+
+console.log(greeting);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..ba47727e0 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,15 @@
 // Start by creating a variable `message`
 
+var firstName = "Gulnihal";
+
+var firstNameLength = firstName.length;
+
+
+console.log(firstNameLength);
+
+var message = "My name is Gulnihal and my name is 8 characters long"
+
 console.log(message);
+
+var noSpaceMessage = message.trim;
+console.log(noSpaceMessage);
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..85fd91b11 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,4 @@
-const name = " Daniel  ";
-
-console.log(message);
+const name = " Gulnihal  ";
+var message = "My name is Gulnihal and my name is 8 characters long"
+var noSpace = message.trim;
+console.log(noSpace);
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..efae065dd 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,5 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+var numberOfStudents =30;
+var numberOfMentors = 16;
+var totalNumberOfStudentsAndMentors = numberOfStudents + numberOfMentors;
+console.log(totalNumberOfStudentsAndMentors);
\ No newline at end of file
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..3925befa7 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,17 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+
+
+// var preciseAge = 30.612437;
+// var roughAge = Math.round(preciseAge);
+// console.log(roughAge);
+
+var proportionStudents = (numberOfStudents / (numberOfStudents + numberOfMentors)) *100;
+console.log(proportionStudents);
+var roughProportionStudents = Math.round(proportionStudents);
+console.log(roughProportionStudents);
+
+var proportionMentors = (numberOfMentors / (numberOfStudents + numberOfMentors)) *100;
+console.log(proportionMentors);
+var roughProportionMentors = Math.round(proportionMentors);
+console.log(roughProportionMentors);
\ No newline at end of file
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..22d2db355 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; // complete the function here
 }
 
 var result = halve(12);
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..0328dc2d7 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; // complete function here
 }
 
 var result = triple(12);
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..79bb0c532 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(num1, num2) {
+ return num1 * num2; // Calculate the result of the function and return it
 }
 
 // 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..9d2cfb53d 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;
+}// Declare your function first
 
 var result = divide(3, 4);
 
diff --git a/exercises/K-functions-parameters/exercise3.js b/exercises/K-functions-parameters/exercise3.js
index 537e9f4ec..503e72b42 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,3 +1,6 @@
+function createGreeting(name) {
+    return "Hello, my name is " + name;
+}
 // Write your function here
 
 var greeting = createGreeting("Daniel");
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..e471c1a24 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,8 @@
+function add(num1, num2){
+    return num1 + num2;
+}
 // Declare your function first
 
 // Call the function and assign to a variable `sum`
-
+var 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..87fee99ab 100644
--- a/exercises/K-functions-parameters/exercise5.js
+++ b/exercises/K-functions-parameters/exercise5.js
@@ -1,3 +1,6 @@
+function createLongGreeting (name, age){
+    return "Hello, my name is " + name + " and I'm " +age + " years old"
+}
 // Declare your function here
 
 const greeting = createLongGreeting("Daniel", 30);
diff --git a/exercises/L-functions-nested/exercise.js b/exercises/L-functions-nested/exercise.js
index a5d377442..a4a92b62c 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -3,3 +3,21 @@ var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+
+function nameUpperCase(mentor) {
+    return mentor.toUpperCase();
+}
+function greeting(name){
+    let message = "HELLO " + nameUpperCase(name);
+    return message;
+}
+
+console.log(greeting(mentor1));
+
+console.log(greeting(mentor2));
+
+console.log(greeting(mentor3));
+
+console.log(greeting(mentor4));
+
+console.log(greeting(mentor5));
diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index 07391e15f..d4310f1a9 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 FORMATTING
@@ -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 BrlToP = parseFloat((price *(99/100) * 5.7).toFixed(2));
+
+  return BrlToP;
+  
+}
 
 /* ======= 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 9c8ebc76a..777950f40 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(number) {
+  return "£" + number;
 }
 
 const startingValue = 2;
 
-// Why can this code be seen as bad practice? Comment your answer.
-let badCode =
+// Why can this code be seen as bad practice? Comment your answer. 
+// bacause: lots of parantheses, and there  are already mathematical symbols to do these operations.
+let badCode = format(multiply((add(startingValue, 10)), 2));
 
 /* BETTER PRACTICE */
 
-let goodCode =
+let goodCode = "£" + ((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/extra/3-magic-8-ball.js b/extra/3-magic-8-ball.js
index 7626877e7..3878e754c 100644
--- a/extra/3-magic-8-ball.js
+++ b/extra/3-magic-8-ball.js
@@ -13,40 +13,45 @@
   and have different levels of positivity or negativity.
 
   Below are the possible answers:
-
-  ## Very positive
-    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.
-
-  ## Very negative
-    Don't count on it.
-    My reply is no.
-    My sources say no.
-    Outlook not so good.
-    Very doubtful.
 */
 
+  // ## Very positive
+  let answers = [
+    "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.",
+
+  // ## Very negative
+    "Don't count on it.",
+    "My reply is no.",
+    "My sources say no.",
+    "Outlook not so good.",
+    "Very doubtful."
+  ];
+
+
 // This should log "The ball has shaken!"
 // and return the answer.
 function shakeBall() {
-  //Write your code in here
+  console.log("The ball has shaken!")
+  var index = Math.floor(Math.random()*answers.length);
+  return answers[index];
 }
 
 /* 
@@ -59,7 +64,23 @@ function shakeBall() {
   This function should expect to be called with any value which was returned by the shakeBall function.
 */
 function checkAnswer(answer) {
-  //Write your code in here
+    let index = answers.indexOf(answer);
+
+    return index <5 ? "very positive"
+          :index <10 ? "positive"
+          :index <15 ? "negative"
+          : "very negative";
+
+    // if (index <5){
+    //   return "very positive";
+    // } else if (index >= 5 && index <10) {
+    //   return "positive";
+    // } else if (index >= 10 && index <15) {
+    //   return "negative";
+    // } else {
+    //   return "very negative";
+    // }
+//Write your code in here
 }
 
 /* 
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index a10cc9ac2..98360ac6b 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";
+}
 
 function getTotal(a, b) {
-  total = a ++ b;
+  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 b90d41dd1..a7235f9bb 100644
--- a/mandatory/2-logic-error.js
+++ b/mandatory/2-logic-error.js
@@ -1,16 +1,16 @@
 // 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();
+function getStringLength(word) {
+  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..e48995a0f 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,14 +1,15 @@
 // Add comments to explain what this function does. You're meant to use Google!
-function getRandomNumber() {
+function getRandomNumber() { //gets random numbers
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
-function combine2Words(word1, word2) {
+function combine2Words(word1, word2) { //combine two words without space between them
   return word1.concat(word2);
 }
 
 function concatenate(firstWord, secondWord, thirdWord) {
+  return firstWord.concat(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.
 }
@@ -25,13 +26,13 @@ To run the tests for just this one file, type `npm test -- --testPathPattern 3-f
 */
 
 test("concatenate example #1", () => {
-  expect(concatenate("code", "your", "future")).toEqual("code your future");
+  expect(concatenate("code ", "your ", "future")).toEqual("code your future");
 });
 
 test("concatenate example #2", () => {
-  expect(concatenate("I", "like", "pizza")).toEqual("I like pizza");
+  expect(concatenate("I ", "like ", "pizza")).toEqual("I like pizza");
 });
 
 test("concatenate doesn't only accept strings", () => {
-  expect(concatenate("I", "am", 13)).toEqual("I am 13");
+  expect(concatenate("I ", "am ", 13)).toEqual("I am 13");
 });
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..7667cef75 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,9 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
+function calculateSalesTax(price){
+  return price * 1.2;
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +19,11 @@ 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);
+  }
+
+ 
 
 /* 
 ===================================================