diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..c716c89fe 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1,2 @@
+let greeting = "Hello world";
 console.log("Hello world");
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..be528d2d0 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,3 @@
 // Start by creating a variable `greeting`
-
+let greeting = "Hello world";
 console.log(greeting);
diff --git a/exercises/D-strings/exercise.js b/exercises/D-strings/exercise.js
index 2cffa6a81..9443edbe0 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,6 @@
 // Start by creating a variable `message`
-
+let greeting = "Hello";
+let name = "irina";
+let message = `${greeting} ${name}`;
 console.log(message);
+console.log(irina);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..f4666e044 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,5 @@
 // Start by creating a variable `message`
-
+let name ="irina";
+let nameLenght = name.lenght;
+let message =`my name is ${name} and my name is$ {nameLength} characters long`
 console.log(message);
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..64646ccfc 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,5 @@
 const name = " Daniel  ";
+let trimmedName = name.trim();
+let message = `My name is ${trimmedName} and my name is ${trimmedName.length} characters long`;
 
 console.log(message);
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..1a711d60e 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 = numberOfMentors + numberOfStudents;
+console.log(total);
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..00e02f4cf 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,9 @@
-var numberOfStudents = 15;
-var numberOfMentors = 8;
+let numberOfStudents = 15;
+let numberOfMentors = 8;
+let total = numberOfStudents + numberOfMentors;
+const pOfStudents = Math.round((numberOfStudents / total) * 100);
+const pOfMentors = Math.round((numberOfMentors / total) * 100);
+console.log(`Number of Students: ${numberOfStudents}`);
+console.log(`Number of Mentors: ${numberOfMentors}`);
+console.log(`percentage of students ${pOfStudents}%`);
+console.log(`percentage of mentors ${pOfMentors}%`);
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..4388d061b 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,4 +1,5 @@
 function halve(number) {
+  return number / 2
   // complete the function here
 }
 
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..75d1c2f90 100644
--- a/exercises/J-functions/exercise2.js
+++ b/exercises/J-functions/exercise2.js
@@ -1,4 +1,5 @@
 function triple(number) {
+  return number * 3;
   // complete function here
 }
 
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..f842a131f 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(x, y) {
   // Calculate the result of the function and return it
+  return x * y;
 }
 
 // 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..ab4102430 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..835563ba5 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..dc9636002 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,9 @@
 // Declare your function first
 
+  let sum = 13 +124;
+
+
+
 // Call the function and assign to a variable `sum`
 
 console.log(sum);
diff --git a/exercises/L-functions-nested/README.md b/exercises/L-functions-nested/README.md
index 1c4ae9c8a..c5f451905 100644
--- a/exercises/L-functions-nested/README.md
+++ b/exercises/L-functions-nested/README.md
@@ -9,13 +9,14 @@ function getAgeInDays(age) {
   return age * 365;
 }
 
-function createCreeting(name, age) {
+function createGreeting(name, age) {
   var ageInDays = getAgeInDays(age);
   var message =
     "My Name is " + name + " and I was born over " + ageInDays + " days ago!";
   return message;
 }
-```
+
+
 
 ## Exercise 1
 
@@ -23,12 +24,18 @@ function createCreeting(name, age) {
 - Your program should include a function that spells their name in uppercase, and a function that creates a shouty greeting.
 - Log each greeting to the console.
 
+
+
 ## Expected result
 
 ```
+
 HELLO DANIEL
 HELLO IRINA
 HELLO MIMI
 HELLO ROB
 HELLO YOHANNES
+
+```
+
 ```
diff --git a/exercises/L-functions-nested/exercise.js b/exercises/L-functions-nested/exercise.js
index a5d377442..01a80fc98 100644
--- a/exercises/L-functions-nested/exercise.js
+++ b/exercises/L-functions-nested/exercise.js
@@ -1,5 +1,27 @@
+function createGreeting(name, age) {
+  return `hello my name is ${name} and I am ${age} years old`;
+}
+let greeting = createGreeting("Daniel", 30);
+console.log(greeting);
+
+
+
+
+
 var mentor1 = "Daniel";
 var mentor2 = "Irina";
 var mentor3 = "Mimi";
 var mentor4 = "Rob";
 var mentor5 = "Yohannes";
+
+
+function mentorGreeting(name) {
+  let getUpperCase = name.toUpperCase();
+  return `Hello ${getUpperCase}`;
+}
+
+console.log(mentorGreeting(mentor1));
+console.log(mentorGreeting(mentor2));
+console.log(mentorGreeting(mentor3));
+console.log(mentorGreeting(mentor4));
+console.log(mentorGreeting(mentor5));
\ No newline at end of file
diff --git a/extra/2-piping.js b/extra/2-piping.js
index b4f8c4c1b..47e6a172f 100644
--- a/extra/2-piping.js
+++ b/extra/2-piping.js
@@ -16,15 +16,18 @@
   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() {
+  return 
 
 }
 
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index a10cc9ac2..6e29e952c 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;
+  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..c27b3d55f 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!
+// Math.random will create a random number between 0 and 1, therefore the function will generate a random number between 0 and 1 and then multiply it by 10
 function getRandomNumber() {
   return Math.random() * 10;
 }
 
 // Add comments to explain what this function does. You're meant to use Google!
+// The word1.concat(word2) function will combine 2 strings together.
 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..a754eca38 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(priceBeforeTax) {
+  return priceBeforeTax + (priceBeforeTax * 0.2);
+  
+}
+
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +21,11 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(priceBeforeTax) {
+let priceAfterTax = calculateSalesTax(priceBeforeTax);
+return `£${priceAfterTax.toFixed(2)}`;
+}
+console.log(addTaxAndFormatCurrency(100));
 
 /* 
 ===================================================