diff --git a/exercises/B-hello-world/exercise.js b/exercises/B-hello-world/exercise.js
index b179ee953..91c5b702a 100644
--- a/exercises/B-hello-world/exercise.js
+++ b/exercises/B-hello-world/exercise.js
@@ -1 +1 @@
-console.log("Hello world");
+console.log('Hello World. I just started learning JavaScript!');
diff --git a/exercises/C-variables/exercise.js b/exercises/C-variables/exercise.js
index a6bbb9786..eccb4e25f 100644
--- a/exercises/C-variables/exercise.js
+++ b/exercises/C-variables/exercise.js
@@ -1,3 +1,7 @@
 // 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..3a5807781 100644
--- a/exercises/D-strings/exercise.js
+++ b/exercises/D-strings/exercise.js
@@ -1,3 +1,4 @@
-// Start by creating a variable `message`
-
+let message = "This is a string";
 console.log(message);
+console.log(typeof message); // string
+
diff --git a/exercises/E-strings-concatenation/exercise.js b/exercises/E-strings-concatenation/exercise.js
index 2cffa6a81..219e0c574 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`
+let name = 'Delroy';
+let greeting = 'Hello';
+
+console.log(greeting + " " + name);
 
-console.log(message);
diff --git a/exercises/F-strings-methods/exercise.js b/exercises/F-strings-methods/exercise.js
index 2cffa6a81..5d78cb2bf 100644
--- a/exercises/F-strings-methods/exercise.js
+++ b/exercises/F-strings-methods/exercise.js
@@ -1,3 +1,4 @@
-// Start by creating a variable `message`
+let name = 'Delroy';
+
+console.log("My name is " + name + " and my name is " + name.length + " characters long");
 
-console.log(message);
diff --git a/exercises/F-strings-methods/exercise2.js b/exercises/F-strings-methods/exercise2.js
index b4b46943d..5ef7872dd 100644
--- a/exercises/F-strings-methods/exercise2.js
+++ b/exercises/F-strings-methods/exercise2.js
@@ -1,3 +1,5 @@
-const name = " Daniel  ";
+const aname = " Daniel  ";
+let myname = aname.trim();
+
+console.log("My name is " + myname + " and my name is " + myname.length + " characters long");
 
-console.log(message);
diff --git a/exercises/G-numbers/exercise.js b/exercises/G-numbers/exercise.js
index 49e7bc00b..4904b21a0 100644
--- a/exercises/G-numbers/exercise.js
+++ b/exercises/G-numbers/exercise.js
@@ -1 +1,8 @@
-// Start by creating a variables `numberOfStudents` and `numberOfMentors`
+let numberOfStudents = 78;
+let numberOfMentors = 7;
+let sum = numberOfStudents + numberOfMentors;
+
+console.log("Number of students: "+numberOfStudents);
+console.log("Number of mentors: "+numberOfMentors);
+console.log("Total number of students and mentors: "+(numberOfStudents+numberOfMentors));
+
diff --git a/exercises/I-floats/exercise.js b/exercises/I-floats/exercise.js
index a5bbcd852..3cadf32ed 100644
--- a/exercises/I-floats/exercise.js
+++ b/exercises/I-floats/exercise.js
@@ -1,2 +1,7 @@
-var numberOfStudents = 15;
-var numberOfMentors = 8;
+let numberOfStudents = 15;
+let numberOfMentors = 8;
+let sum = numberOfStudents + numberOfMentors;
+
+console.log("Percentage students: "+Math.round(numberOfMentors / sum * 100) + '%');
+console.log("Percentage mentors: "+Math.round(numberOfStudents  / sum * 100) + '%');
+
diff --git a/exercises/J-functions/exercise.js b/exercises/J-functions/exercise.js
index 0ae5850e5..c028b6b67 100644
--- a/exercises/J-functions/exercise.js
+++ b/exercises/J-functions/exercise.js
@@ -1,7 +1,13 @@
 function halve(number) {
-  // complete the function here
+  return number / 2;
 }
 
-var result = halve(12);
+let result = halve(12);
+console.log(result);
+
+result = halve(-77);
+console.log(result);
 
+result = halve(34);
 console.log(result);
+
diff --git a/exercises/J-functions/exercise2.js b/exercises/J-functions/exercise2.js
index 82ef5e780..05b858b62 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);
 
 console.log(result);
+
diff --git a/exercises/K-functions-parameters/exercise.js b/exercises/K-functions-parameters/exercise.js
index 8d5db5e69..da2b4cc06 100644
--- a/exercises/K-functions-parameters/exercise.js
+++ b/exercises/K-functions-parameters/exercise.js
@@ -1,9 +1,11 @@
 // Complete the function so that it takes input parameters
-function multiply() {
+function multiply(a,b) {
   // Calculate the result of the function and return it
+  return a * b;
 }
 
 // Assign the result of calling the function the variable `result`
 var 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..aaeb981a5 100644
--- a/exercises/K-functions-parameters/exercise2.js
+++ b/exercises/K-functions-parameters/exercise2.js
@@ -1,5 +1,9 @@
 // Declare your function first
+function divide(m,n) {
+    return m / n;
+}
 
 var 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..3c8df3493 100644
--- a/exercises/K-functions-parameters/exercise3.js
+++ b/exercises/K-functions-parameters/exercise3.js
@@ -1,5 +1,9 @@
 // Write your function here
+function createGreeting(string) {
+    return "Hello, my name is " + string;
+}
 
-var greeting = createGreeting("Daniel");
+let greeting = createGreeting("Daniel");
 
 console.log(greeting);
+
diff --git a/exercises/K-functions-parameters/exercise4.js b/exercises/K-functions-parameters/exercise4.js
index 7ab44589e..3c817d10a 100644
--- a/exercises/K-functions-parameters/exercise4.js
+++ b/exercises/K-functions-parameters/exercise4.js
@@ -1,5 +1,11 @@
 // Declare your function first
 
+function add(m,n) {
+    return m + n;
+}
+
 // 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..64e12e1a1 100644
--- a/exercises/K-functions-parameters/exercise5.js
+++ b/exercises/K-functions-parameters/exercise5.js
@@ -1,5 +1,32 @@
 // Declare your function here
 
+function createLongGreeting(string,number) {
+    return "Hello, my name is " + string + " and I'm " + number + " years old";
+}
+
 const greeting = createLongGreeting("Daniel", 30);
 
 console.log(greeting);
+
+https://github.com/CodeYourFuture/JavaScript-Core-1-Coursework-Week1/tree/master/exercises/L-functions-nested 
+
+function UpperCase(string) {
+  return string.toUpperCase();
+}
+
+function shoutyGreeting(name) {
+   let message = "HELLO " + UpperCase(name);
+  return message;
+}
+
+let mentor1 = "Daniel";
+let mentor2 = "Irina";
+let mentor3 = "Mimi";
+let mentor4 = "Rob";
+let mentor5 = "Yohannes";
+console.log(shoutyGreeting(mentor1));
+console.log(shoutyGreeting(mentor2));
+console.log(shoutyGreeting(mentor3));
+console.log(shoutyGreeting(mentor4));
+console.log(shoutyGreeting(mentor5));
+
diff --git a/mandatory/1-syntax-errors.js b/mandatory/1-syntax-errors.js
index a10cc9ac2..c1eaec4ca 100644
--- a/mandatory/1-syntax-errors.js
+++ b/mandatory/1-syntax-errors.js
@@ -1,27 +1,25 @@
 // 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;
 }
 
 /* 
 ===================================================
 ======= TESTS - DO NOT MODIFY BELOW THIS LINE =====
-
 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 1-syntax-errors` into your terminal
 (Reminder: You must have run `npm install` one time before this will work!)
-
 ===================================================
 */
 
@@ -37,4 +35,4 @@ test("introduceMe function returns the correct string", () => {
 
 test("getTotal returns a string describing the total", () => {
   expect(getTotal(23, 5)).toEqual("The total is 28");
-});
+});
\ No newline at end of file
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..ba8418265 100644
--- a/mandatory/3-function-output.js
+++ b/mandatory/3-function-output.js
@@ -1,9 +1,9 @@
-// Add comments to explain what this function does. You're meant to use Google!
+// This generates a random number then multiplies it by 10; then returns the result
 function getRandomNumber() {
   return Math.random() * 10;
 }
 
-// Add comments to explain what this function does. You're meant to use Google!
+// This takes 2 strings and joins them together, returning the result
 function combine2Words(word1, word2) {
   return word1.concat(word2);
 }
@@ -11,6 +11,7 @@ function combine2Words(word1, word2) {
 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;
 }
 
 /* 
diff --git a/mandatory/4-tax.js b/mandatory/4-tax.js
index ba77c7ae2..df06f09f3 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+price*20/100
+}
 
 /*
   CURRENCY FORMATTING
@@ -17,7 +19,14 @@ function calculateSalesTax() {}
   Remember that the prices must include the sales tax (hint: you already wrote a function for this!)
 */
 
-function addTaxAndFormatCurrency() {}
+function addTaxAndFormatCurrency(number) {
+
+    number = calculateSalesTax(number);
+  
+
+// The toFixed() method rounds a number to a given number of digits.
+    return "£" + number.toFixed(2);
+}
 
 /* 
 ===================================================