diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..7401145e0 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1,6 @@
 console.log("Hello world");
+console.log("Hello World. I just started learning JavaScript!.");
+//console.log(Hello World. I just started learning JavaScript!.); // got a SyntaxError for this one .
+console.log("44");
+console.log(44);
+
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..53b80d5ed 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `greeting`
+const greeting = "Good morning js";
 
 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..97dd813cf 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `message`
-
+const message = "this is a string"
 console.log(message);
+console.log(typeof(message));
+
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..4571a4a46 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 = "Good morning, my name is ";
+const myName = "Halla";
+let message = greetingStart + myName;
 console.log(message);
+console.log(greetingStart + myName);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..a6a5f6c3d 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,16 @@
 // Start by creating a variable `message`
+let myName = " Halla ";
+let message = myName.length;
+let aboutName = `My name is Halla and my name is ${message} characters long`;
+let aboutName1 =
+  "My name is Halla and my name is " + message + " characters long";
+let myNewName = myName.trim();
+let message1 = myNewName.length;
+let aboutName2 =
+  "My name is Halla and my name after trim is " + message1 + " characters long";
 
+console.log(aboutName);
+console.log(aboutName1);
+console.log(aboutName2);
 console.log(message);
+console.log(myName);
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..2e9192b10 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,6 @@
-const name = " Daniel  ";
-
-console.log(message);
+const myName = " Daniel  ";
+let myNewName = myName.trim();
+let message1 = myNewName.length;
+let aboutmyName =
+  "My name is Daniel and my name after trim is " + message1 + " characters long";
+  console.log(aboutmyName);
\ No newline at end of file
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..db37e7443 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,5 @@
 // Start by creating a variables `numberOfStudents` and `numberOfMentors`
+const numberOfStudents = 15;
+const numberOfMentors = 8;
+const total = 23;
+console.log(total);
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..8a33b33d3 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,7 @@
-var numberOfStudents = 15;
-var numberOfMentors = 8;
+const numberOfStudents = 15;
+const numberOfMentors = 8;
+const studentPercent = Math.round((15 / 23) * 100);
+const mentorsPercent = Math.round((8 / 23) * 100);
+
+console.log(`Student Percentage: ${studentPercent}%`);
+console.log(`Mentors Percentage: ${mentorsPercent}%`);
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..baf355ec9 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,7 +1,9 @@
 function halve(number) {
-  // complete the function here
+  return number / 2;
 }
 
-var result = halve(12);
+const result = halve(12);
 
 console.log(result);
+console.log(halve(24));
+console.log(halve(44));
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..ff38f3867 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);
-
+const result = triple(12);
+triple(3);
 console.log(result);
+console.log(triple(3));
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..3d3885c1e 100644
--- a/exercises/K-functions-parameters/exercise.js
+++ b/exercises/K-functions-parameters/exercise.js
@@ -1,9 +1,9 @@
 // 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);
+const result = multiply(3, 4);
 
 console.log(result);
diff --git a/exercises/K-functions-parameters/exercise2.js b/exercises/K-functions-parameters/exercise2.js
index db7a8904b..0470bc7f3 100644
--- a/exercises/K-functions-parameters/exercise2.js
+++ b/exercises/K-functions-parameters/exercise2.js
@@ -1,5 +1,6 @@
-// Declare your function first
-
-var result = divide(3, 4);
+function divide(a, b) {
+  return a / b;
+}
+const result = divide(3, 4);
 
 console.log(result);
diff --git a/exercises/K-functions-parameters/exercise3.js b/exercises/K-functions-parameters/exercise3.js
index 537e9f4ec..04fbc89f3 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,5 +1,7 @@
-// Write your function here
-
-var greeting = createGreeting("Daniel");
+function createGreeting(name){
+ return "Good morning " + name ;
+}
+let greeting = createGreeting("Daniel");
 
 console.log(greeting);
+console.log(createGreeting("Halla"));
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..79c45f8a5 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,7 @@
-// Declare your function first
-
+function adding(a, b) {
+  return a + b;
+}
+const sum = adding(13, 124);
 // Call the function and assign to a variable `sum`
 
 console.log(sum);
diff --git a/exercises/K-functions-parameters/exercise5.js b/exercises/K-functions-parameters/exercise5.js
index 7c5bcd605..796e5f10a 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(myname, Age) {
+  return "Hello, my name is " + myname + " 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..0ecf0d98c 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -3,3 +3,15 @@ var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+function upperCase(name1){
+  return name1.toUpperCase();
+}
+
+function greeting(name1){
+  return "HELLO "+ upperCase(name1);
+}
+console.log(greeting("daniel"));
+console.log(greeting("Irina"));
+console.log(greeting("Mimi"));
+console.log(greeting("Rob"));
+console.log(greeting("Yohannes"));
\ No newline at end of file
diff --git a/extra/1-currency-conversion.js b/extra/1-currency-conversion.js
index d82e59480..2bcc0ae4f 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(moneyToDollar) {
+  return moneyToDollar * 1.4;
+}
 
 /*
   CURRENCY CONVERSION
@@ -15,12 +17,16 @@ 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(moneyToReal) {
+  moneyToReal = moneyToReal * 0.99 * 5.7;
+  /* Rounding to the nearest hundredths .*/
+  return Math.round(100 * moneyToReal) / 100;
+}
 
 /* ======= TESTS - DO NOT MODIFY ===== 
 There are some Tests in this file that will help you work out if your code is working.
 
-To run these tests type `npm run extraTo run the tests for just this one file, type `npm run extra-tests -- --testPathPattern 1-syntax-errors` into your terminal
+To run these tests type `npm run extraTo run the tests for just this one file, type `npm run extra-tests -- --testPathPattern 1-currency-conversion` into your terminal
 (Reminder: You must have run `npm install` one time before this will work!)
 */
 
diff --git a/extra/2-piping.js b/extra/2-piping.js
index 9c8ebc76a..c06c21bcc 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,26 +16,29 @@
   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(number) {
+  return `£${number}`;
 }
 
 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 looks more complex than the goodCode .
 
 /* BETTER PRACTICE */
+const adding = add(startingValue, 10);
+const multiplying = multiply(adding, 2);
 
-let goodCode =
+let goodCode = format(multiplying);
 
 /* ======= 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 f3adbefa5..1e3ddd294 100644
--- a/extra/3-magic-8-ball.js
+++ b/extra/3-magic-8-ball.js
@@ -45,8 +45,34 @@
 
 // This should log "The ball has shaken!"
 // and return the answer.
+
 function shakeBall() {
-  //Write your code in here
+  expectedAnswers = [
+    "It is certain.",
+    "It is decidedly so.",
+    "Without a doubt.",
+    "Yes - definitely.",
+    "You may rely on it.",
+    "As I see it, yes.",
+    "Most likely.",
+    "Outlook good.",
+    "Yes.",
+    "Signs point to yes.",
+    "Reply hazy, try again.",
+    "Ask again later.",
+    "Better not tell you now.",
+    "Cannot predict now.",
+    " Concentrate and ask again.",
+    "Don't count on it.",
+    "My reply is no.",
+    " My sources say no.",
+    "Outlook not so good.",
+    "Very doubtful.",
+  ];
+  console.log("The ball has shaken!");
+  let random1 = Math.floor(Math.random() * 20);
+  let answer = expectedAnswers[random1];
+  return answer;
 }
 
 /* 
@@ -59,7 +85,15 @@ 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
+  if (expectedAnswers.indexOf(answer) <= 4) {
+    return "very positive";
+  } else if (expectedAnswers.indexOf(answer) <= 9) {
+    return "positive";
+  } else if (expectedAnswers.indexOf(answer) <= 14) {
+    return "negative";
+  } else {
+    return "very negative";
+  }
 }
 
 /* 
@@ -101,7 +135,9 @@ test("magic 8 ball returns different values each time", () => {
     );
   }
 
-  let seenPositivities = new Set(Array.from(seenAnswers.values()).map(checkAnswer));
+  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"
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 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..08ae388ee 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,14 +1,17 @@
 // Add comments to explain what this function does. You're meant to use Google!
+//This function returns a random number between 0 (included) and 10 (excluded):
 function getRandomNumber() {
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
+// this function join two strings
 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..644fb2e6b 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) {
+  let newPrice = calculateSalesTax(price);
+  let newPriceDecimal = newPrice.toFixed(2);
+  return `£${newPriceDecimal}`;
+}
 
 /* 
 ===================================================