diff --git a/exercises/B-hello-world/README.md b/exercises/B-hello-world/README.md
index 27282c4af..c9553e9fe 100644
--- a/exercises/B-hello-world/README.md
+++ b/exercises/B-hello-world/README.md
@@ -5,9 +5,7 @@ We'll do this in JavaScript, using something called `console.log()`.
 Inside of `exercise.js` there's a line of code that will print "Hello world!".
 
 ### 1. Run the program
-
-- Open a terminal window
-- Change directory to this folder (`cd exercises/B-hello-world`) - assuming you're at the project root
+('cd exercises/B-hello-world`) - assuming you're at the project root
 - Run the program using node (`node exercise.js`)
 
 ### 2. Experiment
diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..06559e909 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');
+console.log("hello there!!!");
+console.log("finally working!");
+console.log("not working");
diff --git a/exercises/C-variables/README.md b/exercises/C-variables/README.md
index 40859b3a8..6f9831e23 100644
--- a/exercises/C-variables/README.md
+++ b/exercises/C-variables/README.md
@@ -15,7 +15,7 @@ The program above will print "Hello world" to the console. Notice how it uses th
 - Add a variable `greeting` to exercise.js (make sure it comes _before_ the console.log)
 - Print your `greeting` to the console 3 times
 
-> Remember: to run this exercise you must change directory to the `C-variables`. If you already have a terminal window open for the previous exercise you can do this by running the command `cd ../C-variables`.
+> Remember: to run this exercise you must change directory to the `C-variables`. If you already have a terminal window open for the previous exercise you can do this by running the command ``.
 
 ## Expected result
 
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..05d1639e5 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,3 @@
 // Start by creating a variable `greeting`
-
-console.log(greeting);
+let greeting = "Isn't good day at all!"
+console.log(greeting);
\ No newline at end of file
diff --git a/exercises/D-strings/exercise.js b/exercises/D-strings/exercise.js
index 2cffa6a81..4c13b2cc5 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `message`
+var message = "This is a string string"
 
-console.log(message);
+var messageType = typeof message;
+
+console.log(messageType);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..44b403783 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 greeting = "Good day, my name is ";
+var myName = "Catalina";
+var message = greeting + myName;
 console.log(message);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..4a105a07a 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`
+var message1 = "My name is Catalina-Alexandra and my name is ";
+var message2 = " characters long";
+var myName = "Catalina-Alexandra";
+var nameLength = myName.length;
+var message = message1 + nameLength + message2;
 
 console.log(message);
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..8ecbcd84d 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,11 @@
-const name = " Daniel  ";
+const myName = " Catalina-Alexandra  ";
+const trimmed = myName.trim();
+var message1 = "My name is ";
+var message2 = " and my name is ";
+var message3 = " characters long";
+
+var nameLength = myName.length;
+var message = message1 + trimmed + message2 + nameLength + message3;
+
 
 console.log(message);
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..e090fb71c 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,7 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+var numberOfStudents = 30 + 2;
+var numberOfMentors = 8 + 1;
+var total = numberOfStudents + numberOfMentors;
+console.log("Number of students: " + numberOfStudents);
+console.log("Number of mentors: " + numberOfMentors);
+console.log("Total number of students and mentors: " + total);
\ No newline at end of file
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..3b242adf9 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,9 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+var proNrOfStudents = 1500 / 23;
+var proNrOfMentors = 800 / 23;
+var proNrOfStudentsRound = Math.round(proNrOfStudents);
+var proNrOfMentorsRound = Math.round(proNrOfMentors);
+
+console.log("Procent of students: " + proNrOfStudentsRound + "%");
+console.log("Procent of mentors: " + proNrOfMentorsRound + "%");
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..e8e791318 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,7 +1,8 @@
 function halve(number) {
   // complete the function here
+  return number / 2;
 }
 
-var result = halve(12);
+var result = halve(200);
 
 console.log(result);
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..29b2e6e13 100644
--- a/exercises/J-functions/exercise2.js
+++ b/exercises/J-functions/exercise2.js
@@ -1,7 +1,8 @@
 function triple(number) {
   // complete function here
+  return number * 3;
 }
 
-var result = triple(12);
+var result = triple(7);
 
 console.log(result);
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..a4eed9d76 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..4805ef7dc 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(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..8644dc78b 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,5 +1,8 @@
 // Write your function here
+function createGreeting(myName) {
+    return "Hello, my name is  " + myName;
+}
 
-var greeting = createGreeting("Daniel");
+var greeting = createGreeting("Catalina");
 
 console.log(greeting);
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..e43f0852a 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,8 @@
 // Declare your function first
+function addition(nr1, nr2) {
+    return nr1 + nr2;
+}
 
 // Call the function and assign to a variable `sum`
-
+var sum = addition(13, 124);
 console.log(sum);
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..b7534db5c 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(myName, age) {
+    return "Hello, my name is " + myName + " and I'm " + age + " years old."
+}
 
-const greeting = createLongGreeting("Daniel", 30);
+const greeting = createLongGreeting("Catalina", 47);
 
 console.log(greeting);
diff --git a/exercises/L-functions-nested/exercise.js b/exercises/L-functions-nested/exercise.js
index a5d377442..1493c896e 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -3,3 +3,18 @@ var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+
+function upCase(name) {
+    return name.toUpperCase();
+}
+function greeting(name) {
+    let shouty = upCase(name);
+    let message = "GOOD DAY " + shouty;
+    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 75b3c6aab..2dea27760 100644
--- a/extra/1-currency-conversion.js
+++ b/extra/1-currency-conversion.js
@@ -5,8 +5,11 @@
   Write a function that converts a price to USD (exchange rate is 1.4 $ to £)
 */
 
-function convertToUSD() {}
+function convertToUSD(pound) {
+  return pound * 1.4;
 
+}
+console.log(convertToUSD(32))
 /*
   CURRENCY CONVERSION
   ===================
@@ -15,8 +18,10 @@ 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(pound) {
+  return pound * 5.7;
+}
+console.log(convertToBRL(30));
 /* ======= 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..d8a17d061 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,58 +16,62 @@
   the final result to the variable goodCode
 */
 
-function add() {
+// function add(2, 4) {
+//   return 2 + 4;
 
-}
+// }
 
-function multiply() {
+// function multiply(5, 6) {
+//   return 5 * 6;
 
-}
+// }
 
-function format() {
+// function format($, 20) {
+//   return "$" + "20"
 
-}
+// }
 
-const startingValue = 2;
+// 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.
+// let badCode =
 
-/* BETTER PRACTICE */
+//   /* BETTER PRACTICE */
 
-let goodCode =
 
-/* ======= TESTS - DO NOT MODIFY ===== 
-There are some Tests in this file that will help you work out if your code is working.
+//   let goodCode =
 
-To run the tests for just this one file, type `npm test -- --testPathPattern 2-piping` into your terminal
-(Reminder: You must have run `npm install` one time before this will work!)
-*/
+//     /* ======= TESTS - DO NOT MODIFY ===== 
+//     There are some Tests in this file that will help you work out if your code is working.
+    
+//     To run the tests for just this one file, type `npm test -- --testPathPattern 2-piping` into your terminal
+//     (Reminder: You must have run `npm install` one time before this will work!)
+//     */
 
-test("add function - case 1 works", () => {
-  expect(add(1, 3)).toEqual(4);
-});
+//     test("add function - case 1 works", () => {
+//       expect(add(1, 3)).toEqual(4);
+//     });
 
-test("add function - case 2 works", () => {
-  expect(add(2.4, 5)).toEqual(7.4);
-});
+// test("add function - case 2 works", () => {
+//   expect(add(2.4, 5)).toEqual(7.4);
+// });
 
-test("multiply function works", () => {
-  expect(multiply(2, 3)).toEqual(6);
-});
+// test("multiply function works", () => {
+//   expect(multiply(2, 3)).toEqual(6);
+// });
 
-test("format function works for whole number", () => {
-  expect(format(16)).toEqual("£16");
-});
+// test("format function works for whole number", () => {
+//   expect(format(16)).toEqual("£16");
+// });
 
-test("format function works for decimal number", () => {
-  expect(format(10.1)).toEqual("£10.1");
-});
+// test("format function works for decimal number", () => {
+//   expect(format(10.1)).toEqual("£10.1");
+// });
 
-test("badCode variable correctly assigned", () => {
-  expect(badCode).toEqual("£24");
-});
+// test("badCode variable correctly assigned", () => {
+//   expect(badCode).toEqual("£24");
+// });
 
-test("goodCode variable correctly assigned", () => {
-  expect(goodCode).toEqual("£24");
-});
+// test("goodCode variable correctly assigned", () => {
+//   expect(goodCode).toEqual("£24");
+// });
diff --git a/extra/3-magic-8-ball.js b/extra/3-magic-8-ball.js
index 46f65f928..ea835f8ad 100644
--- a/extra/3-magic-8-ball.js
+++ b/extra/3-magic-8-ball.js
@@ -1,118 +1,119 @@
-/**
-
-  Let's peer into the future using a Magic 8 Ball!
-  https://en.wikipedia.org/wiki/Magic_8-Ball 
-
-  There are a few steps to being able view the future though:
-  * Ask a question
-  * Shake the ball
-  * Get an answer
-  * Decide if it's positive or negative
-
-  The question can be anything, but the answers are fixed,
-  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.
-*/
-
-// This should log "The ball has shaken!"
-// and return the answer.
-function shakeBall() {
-  //Write your code in here
-}
-
-/* 
-  This function should say whether the answer it is given is
-    - very positive
-    - positive
-    - negative
-    - very negative
-
-  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
-}
-
-/* 
-==================================
-======= TESTS - DO NOT MODIFY =====
-
-There are some Tests in this file that will help you work out if your code is working.
-
-To run the tests for just this one file, type `npm test -- --testPathPattern 3-magic-8-ball` into your terminal
-(Reminder: You must have run `npm install` one time before this will work!)
-==================================
-*/
-
-test("whole magic 8 ball sequence", () => {
-  const consoleLogSpy = jest.spyOn(global.console, "log");
-  const answer = shakeBall();
-
-  expect(typeof answer).toEqual("string");
-
-  expect(consoleLogSpy).toHaveBeenCalledTimes(1);
-  expect(consoleLogSpy).toHaveBeenLastCalledWith("The ball has shaken!");
-
-  expect(checkAnswer(answer)).toBeOneOf([
-    "very positive",
-    "positive",
-    "negative",
-    "very negative",
-  ]);
-});
-
-test("magic 8 ball returns different values each time", () => {
-  const seenAnswers = new Set();
-  for (let i = 0; i < 10; ++i) {
-    seenAnswers.add(shakeBall());
-  }
-  if (seenAnswers.size < 2) {
-    throw Error(
-      "Expected to get different random answers each time shakeBall was called, but always got the same one"
-    );
-  }
-
-  let seenPositivities = new Set(Array.from(seenAnswers.values()).map(checkAnswer));
-  if (seenPositivities.size < 2) {
-    throw Error(
-      "Expected to random answers with different positivities each time shakeBall was called, but always got the same one"
-    );
-  }
-});
-
-test("checkAnswer works for `It is decidedly so.`", () => {
-  expect(checkAnswer("It is decidedly so.")).toEqual("very positive");
-});
-
-test("checkAnswer works for `My reply is no.`", () => {
-  expect(checkAnswer("My reply is no.")).toEqual("very negative");
-});
+// /**
+
+//   Let's peer into the future using a Magic 8 Ball!
+//   https://en.wikipedia.org/wiki/Magic_8-Ball
+
+//   There are a few steps to being able view the future though:
+//   * Ask a question
+//   * Shake the ball
+//   * Get an answer
+//   * Decide if it's positive or negative
+
+//   The question can be anything, but the answers are fixed,
+//   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.
+// */
+
+// // This should log "The ball has shaken!"
+// // and return the answer.
+// function shakeBall() {
+//   //Write your code in here
+
+// }
+
+// /*
+//   This function should say whether the answer it is given is
+//     - very positive
+//     - positive
+//     - negative
+//     - very negative
+
+//   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
+// }
+
+// /*
+// ==================================
+// ======= TESTS - DO NOT MODIFY =====
+
+// There are some Tests in this file that will help you work out if your code is working.
+
+// To run the tests for just this one file, type `npm test -- --testPathPattern 3-magic-8-ball` into your terminal
+// (Reminder: You must have run `npm install` one time before this will work!)
+// ==================================
+// */
+
+// test("whole magic 8 ball sequence", () => {
+//   const consoleLogSpy = jest.spyOn(global.console, "log");
+//   const answer = shakeBall();
+
+//   expect(typeof answer).toEqual("string");
+
+//   expect(consoleLogSpy).toHaveBeenCalledTimes(1);
+//   expect(consoleLogSpy).toHaveBeenLastCalledWith("The ball has shaken!");
+
+//   expect(checkAnswer(answer)).toBeOneOf([
+//     "very positive",
+//     "positive",
+//     "negative",
+//     "very negative",
+//   ]);
+// });
+
+// test("magic 8 ball returns different values each time", () => {
+//   const seenAnswers = new Set();
+//   for (let i = 0; i < 10; ++i) {
+//     seenAnswers.add(shakeBall());
+//   }
+//   if (seenAnswers.size < 2) {
+//     throw Error(
+//       "Expected to get different random answers each time shakeBall was called, but always got the same one"
+//     );
+//   }
+
+//   let seenPositivities = new Set(Array.from(seenAnswers.values()).map(checkAnswer));
+//   if (seenPositivities.size < 2) {
+//     throw Error(
+//       "Expected to random answers with different positivities each time shakeBall was called, but always got the same one"
+//     );
+//   }
+// });
+
+// test("checkAnswer works for `It is decidedly so.`", () => {
+//   expect(checkAnswer("It is decidedly so.")).toEqual("very positive");
+// });
+
+// test("checkAnswer works for `My reply is no.`", () => {
+//   expect(checkAnswer("My reply is no.")).toEqual("very negative");
+// });
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index a10cc9ac2..578aa9871 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,17 +1,21 @@
 // There are syntax errors in this code - can you fix it to pass the tests?
 
-function addNumbers(a b c) {
-  return a + b + c;
+function addNumbers(a, b, c) {
+  let d = a + b + c;
+  return d;
 }
 
-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`;
+}
+console.log(introduceMe('Catalina', 47));
 
 function getTotal(a, b) {
-  total = a ++ b;
+  let toEqual = a + b;
+  return `The total is ${toEqual}`;
 
-  return "The total is total";
 }
+console.log(getTotal());
 
 /* 
 ===================================================
diff --git a/mandatory/2-logic-error.js b/mandatory/2-logic-error.js
index 9cca7603b..bff42c8ee 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();
+  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..cc5c066e7 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,16 +1,22 @@
-// Add comments to explain what this function does. You're meant to use Google!
+// Add comments to explain what this function does. You're meant to use Google! Math.random() method returns a random number from zero (inclusive)up but not including 1.
 function getRandomNumber() {
-  return Math.random() * 10;
+  return (Math.random() * 10);
 }
 
-// Add comments to explain what this function does. You're meant to use Google!
-function combine2Words(word1, word2) {
-  return word1.concat(word2);
+// Add comments to explain what this function does. You're meant to use Google!Concat()method joins two or more strings.
+function combine2Words(word1, word2, word3) {
+  return word1 + word2 + word3;
 }
 
 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} ${secondWord} ${thirdWord}`;
+}
+function wordsNr(word1, word2, nr) {
+
+  return `${word1} ${word2} ${nr}`;
 }
 
 /* 
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..d8f06eead 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(price) {
+  return price + (price * 0.2);
+
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +20,9 @@ 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 "£" + (price + price * 0.2).toFixed(2);
+}
 
 /* 
 ===================================================