diff --git a/.DS_Store b/.DS_Store
new file mode 100644
index 000000000..3f77b617e
Binary files /dev/null and b/.DS_Store differ
diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 000000000..a5109f603
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+  "cSpell.words": ["Andi", "Andriana"]
+}
diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..1c809b876 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1,7 @@
 console.log("Hello world");
+console.log("Hello World. I just started learning JavaScript!");
+
+//npm test -- --testPathPattern mandatory/1-syntax-errors.js -> run single test
+
+console.log(3);
+console.log(Hello);
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..1fa7db4be 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,6 @@
 // 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..69fe59fc6 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,8 @@
 // Start by creating a variable `message`
-
+const message = "Hello World. This is a string";
 console.log(message);
+console.log(typeof message);
+
+const pounds = 5;
+console.log(pounds);
+console.log(typeof pounds);
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..fd34e8030 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`
+let greetingStart = "Hello, my name is ";
+let name = "Andriana";
+name = "Andi";
+
+const message = greetingStart + name;
 
 console.log(message);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..c60b14ba4 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`
+let name = "Andriana";
+const nameLength = name.length;
+
+console.log(name);
+console.log(nameLength);
+
+let nameLowerCase = name.toLowerCase();
+
+console.log(nameLowerCase);
+
+const message = `  My name is ${name} and my name is ${nameLength} characters long.  `;
 
 console.log(message);
+console.log(message.trim());
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..53fd77db6 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,7 @@
 const name = " Daniel  ";
+const nameLength = name.length;
+
+const message = `  My name is ${name} and my name is ${nameLength} characters long.  `;
 
 console.log(message);
+console.log(message.trim());
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..68c253289 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,7 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+let numberOfStudents = 15;
+let numberOfMentors = 8;
+
+const total = numberOfMentors + numberOfStudents;
+
+console.log(total);
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..55c1ddae9 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,16 @@
 var numberOfStudents = 15;
 var numberOfMentors = 8;
+
+const totalNumber = numberOfMentors + numberOfStudents;
+
+let percentageStudents = (numberOfStudents / totalNumber) * 100;
+const roughPercentageStudents = Math.round(percentageStudents);
+
+console.log(percentageStudents);
+console.log(roughPercentageStudents);
+
+let percentageMentors = (numberOfMentors / totalNumber) * 100;
+const roughPercentageMentors = Math.round(percentageMentors);
+
+console.log(percentageMentors);
+console.log(roughPercentageMentors);
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..fb3832294 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,7 +1,19 @@
 function halve(number) {
-  // complete the function here
+  return number / 2;
 }
 
 var result = halve(12);
 
 console.log(result);
+
+result = halve(10);
+
+console.log(result);
+
+result = halve(8);
+
+console.log(result);
+
+result = halve(6);
+
+console.log(result);
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..457e947af 100644
--- a/exercises/J-functions/exercise2.js
+++ b/exercises/J-functions/exercise2.js
@@ -1,7 +1,19 @@
 function triple(number) {
-  // complete function here
+  return number * 3;
 }
 
 var result = triple(12);
 
 console.log(result);
+
+result = triple(10);
+
+console.log(result);
+
+result = triple(8);
+
+console.log(result);
+
+result = triple(6);
+
+console.log(result);
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..ed88cb68b 100644
--- a/exercises/K-functions-parameters/exercise.js
+++ b/exercises/K-functions-parameters/exercise.js
@@ -1,9 +1,17 @@
 // Complete the function so that it takes input parameters
-function multiply() {
-  // Calculate the result of the function and return it
+function multiply(a, b) {
+  return a * b;
 }
 
 // Assign the result of calling the function the variable `result`
 var result = multiply(3, 4);
 
 console.log(result);
+
+result = multiply(2, 2);
+
+console.log(result);
+
+result = multiply(10, 10);
+
+console.log(result);
diff --git a/exercises/K-functions-parameters/exercise2.js b/exercises/K-functions-parameters/exercise2.js
index db7a8904b..4a5a35dda 100644
--- a/exercises/K-functions-parameters/exercise2.js
+++ b/exercises/K-functions-parameters/exercise2.js
@@ -1,5 +1,19 @@
-// Declare your function first
+function divide(a, b) {
+  return a / b;
+}
 
 var result = divide(3, 4);
 
 console.log(result);
+
+result = divide(10, 2);
+
+console.log(result);
+
+result = divide(72, 3);
+
+console.log(result);
+
+result = divide(1, 2);
+
+console.log(result);
diff --git a/exercises/K-functions-parameters/exercise3.js b/exercises/K-functions-parameters/exercise3.js
index 537e9f4ec..fd7f45539 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,5 +1,19 @@
-// Write your function here
+function createGreeting(name) {
+  return (message = `Hello, my name is ${name}`);
+}
 
 var greeting = createGreeting("Daniel");
 
 console.log(greeting);
+
+greeting = createGreeting("Day");
+
+console.log(greeting);
+
+greeting = createGreeting("Lewis");
+
+console.log(greeting);
+
+greeting = createGreeting("Junior");
+
+console.log(greeting);
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..b9f88f298 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,7 @@
-// Declare your function first
+function add(a, b) {
+  return a + b;
+}
 
-// Call the function and assign to a variable `sum`
+let 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..e57bfbc87 100644
--- a/exercises/K-functions-parameters/exercise5.js
+++ b/exercises/K-functions-parameters/exercise5.js
@@ -1,4 +1,6 @@
-// Declare your function here
+function createLongGreeting(name, age) {
+  return (message = `Hello, my name is ${name} and I'm ${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..31fb8935a 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -3,3 +3,25 @@ var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+
+// ```js
+// var name = "Daniel";
+// var nameLowerCase = name.toLowerCase();
+
+// console.log(nameLowerCase); // "daniel"
+// ```;
+
+function nameUpperCase(name) {
+  return name.toUpperCase();
+}
+
+function shoutyGreeting(name) {
+  let upperCaseName = nameUpperCase(name);
+  return `HELLO ${upperCaseName}`;
+}
+
+console.log(shoutyGreeting(mentor1));
+console.log(shoutyGreeting(mentor2));
+console.log(shoutyGreeting(mentor3));
+console.log(shoutyGreeting(mentor4));
+console.log(shoutyGreeting(mentor5));
diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index 75b3c6aab..8db7ff281 100644
--- a/extra/1-currency-conversion.js
+++ b/extra/1-currency-conversion.js
@@ -5,7 +5,10 @@
   Write a function that converts a price to USD (exchange rate is 1.4 $ to £)
 */
 
-function convertToUSD() {}
+function convertToUSD(price) {
+  let convertGbpToUsd = price * 1.4;
+  return convertGbpToUsd;
+}
 
 /*
   CURRENCY CONVERSION
@@ -15,7 +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(price) {
+  let convertGbpToBrl = (price * 0.99 * 5.7).toFixed(2);
+  return Number(convertGbpToBrl);
+}
 
 /* ======= 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..2b6d9145c 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,26 +16,26 @@
   the final result to the variable goodCode
 */
 
-function add() {
-
+function add(num1, num2) {
+  return num1 + num2;
 }
 
-function multiply() {
-
+function multiply(number1, number2) {
+  return number1 * number2;
 }
 
-function format() {
-
+function format(price) {
+  return `£${price}`;
 }
 
 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)); //This formula for this variable is too complicated and long to read or figure out.
 
 /* 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/extra/3-magic-8-ball.js b/extra/3-magic-8-ball.js
deleted file mode 100644
index 46f65f928..000000000
--- a/extra/3-magic-8-ball.js
+++ /dev/null
@@ -1,118 +0,0 @@
-/**
-
-  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..566b465d0 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 9cca7603b..6f1b1d56b 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 getStringLength(word) {
-  return "word".length();
+  let wordLength = word.length;
+  return wordLength;
 }
 
 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..b3e306216 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -2,13 +2,17 @@
 function getRandomNumber() {
   return Math.random() * 10;
 }
+//The Math.random() method returns a random number from 0 (inclusive) up to but not including 1 (exclusive).
 
 // Add comments to explain what this function does. You're meant to use Google!
 function combine2Words(word1, word2) {
   return word1.concat(word2);
 }
 
+//The concat() method joins two or more strings, it does not change the existing strings but returns a new string.
+
 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..16584e30d 100644
--- a/mandatory/4-tax.js
+++ b/mandatory/4-tax.js
@@ -5,7 +5,11 @@
   Sales tax is 20% of the price of the product.
 */
 
-function calculateSalesTax() {}
+function calculateSalesTax(number) {
+  let salesAmount = number * 0.2;
+  let newSalesAmount = salesAmount + number;
+  return newSalesAmount;
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +21,12 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(number) {
+  let salesTaxPlusAmount = calculateSalesTax(number);
+  let newSalesAmount = salesTaxPlusAmount.toFixed(2);
+  let totalAmount = `£${newSalesAmount}`;
+  return totalAmount;
+}
 
 /* 
 ===================================================