diff --git a/Sprint-3/1-key-errors/0.js b/Sprint-3/1-key-errors/0.js
index 653d6f5a0..b2ced95eb 100644
--- a/Sprint-3/1-key-errors/0.js
+++ b/Sprint-3/1-key-errors/0.js
@@ -1,7 +1,9 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// I predict this code will produce a SyntaxError because str is declared twice in the same scope using let.
 
 // call the function capitalise with a string input
+capitalise("hello");
 // interpret the error message and figure out why an error is occurring
 
 function capitalise(str) {
@@ -10,4 +12,14 @@ function capitalise(str) {
 }
 
 // =============> write your explanation here
+// The error occurs because str is already declared as a parameter
+// Inside the function, let str attempts to declare another variable
+// with the same name in the same scope.
+// We can fix the problem by removing let and assigning the new value
+// directly to the existing parameter.
+
 // =============> write your new code here
+function capitalise(str) {
+  str = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return str;
+}
diff --git a/Sprint-3/1-key-errors/1.js b/Sprint-3/1-key-errors/1.js
index f2d56151f..bea122587 100644
--- a/Sprint-3/1-key-errors/1.js
+++ b/Sprint-3/1-key-errors/1.js
@@ -2,6 +2,8 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
+// An error will occur because `decimalNumber` is declared twice
+// inside the function: once as a parameter and again using `const`.
 
 // Try playing computer with the example to work out what is going on
 
@@ -15,6 +17,16 @@ function convertToPercentage(decimalNumber) {
 console.log(decimalNumber);
 
 // =============> write your explanation here
+// The function already has a parameter called decimalNumber.
+// The line const decimalNumber = 0.5 tries to declare another variable with the same name in the same scope.
+// JavaScript does not allow this, so a SyntaxError occurs.
+// There is also another problem: decimalNumber only exists inside the function, so console.log(decimalNumber) outside the function would cause a ReferenceError.
 
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function convertToPercentage(decimalNumber) {
+  const percentage = `${decimalNumber * 100}%`;
+  return percentage;
+}
+
+console.log(convertToPercentage(0.5));
diff --git a/Sprint-3/1-key-errors/2.js b/Sprint-3/1-key-errors/2.js
index aad57f7cf..4b3397ef9 100644
--- a/Sprint-3/1-key-errors/2.js
+++ b/Sprint-3/1-key-errors/2.js
@@ -4,17 +4,23 @@
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
+// A SyntaxError will occur because 3 is not a valid parameter name.
 
 function square(3) {
     return num * num;
 }
 
 // =============> write the error message here
+// SyntaxError: Unexpected number
 
 // =============> explain this error message here
+// A parameter must be an identifier (variable name), but 3 is a number.
 
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
+function square(num) {
+    return num * num;
+}
 
 
diff --git a/Sprint-3/2-mandatory-debug/0.js b/Sprint-3/2-mandatory-debug/0.js
index b27511b41..96b10a76f 100644
--- a/Sprint-3/2-mandatory-debug/0.js
+++ b/Sprint-3/2-mandatory-debug/0.js
@@ -1,6 +1,9 @@
 // Predict and explain first...
 
 // =============> write your prediction here
+// The output will be:
+// 320
+// The result of multiplying 10 and 32 is undefined
 
 function multiply(a, b) {
   console.log(a * b);
@@ -9,6 +12,14 @@ function multiply(a, b) {
 console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
 
 // =============> write your explanation here
+// multiply(10, 32) runs the function and console.log(a * b) prints 320.
+// However, the function does not have a return statement.
+// A JavaScript function without a return statement returns undefined.
 
 // Finally, correct the code to fix the problem
 //  =============> write your new code here
+function multiply(a, b) {
+  return a * b;
+}
+
+console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
diff --git a/Sprint-3/2-mandatory-debug/1.js b/Sprint-3/2-mandatory-debug/1.js
index 37cedfbcf..834967286 100644
--- a/Sprint-3/2-mandatory-debug/1.js
+++ b/Sprint-3/2-mandatory-debug/1.js
@@ -1,5 +1,6 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// Output: The sum of 10 and 32 is undefined
 
 function sum(a, b) {
   return;
@@ -9,5 +10,12 @@ function sum(a, b) {
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
 
 // =============> write your explanation here
+// Because there is no value after `return`, the function returns undefined.
+// The line a + b is unreachable code, meaning it will never run.
 // Finally, correct the code to fix the problem
 //  =============> write your new code here
+function sum(a, b) {
+  return a + b;
+}
+
+console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
diff --git a/Sprint-3/2-mandatory-debug/2.js b/Sprint-3/2-mandatory-debug/2.js
index 57d3f5dc3..e9be4b966 100644
--- a/Sprint-3/2-mandatory-debug/2.js
+++ b/Sprint-3/2-mandatory-debug/2.js
@@ -2,6 +2,10 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+// Output:
+// The last digit of 42 is 3
+// The last digit of 105 is 3
+// The last digit of 806 is 3
 
 const num = 103;
 
@@ -15,10 +19,21 @@ console.log(`The last digit of 806 is ${getLastDigit(806)}`);
 
 // Now run the code and compare the output to your prediction
 // =============> write the output here
+// The last digit of 42 is 3
+// The last digit of 105 is 3
+// The last digit of 806 is 3
 // Explain why the output is the way it is
 // =============> write your explanation here
+// getLastDigit() does not have a parameter, so the values 42, 105 and 806 passed to it are not being used.
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function getLastDigit(num) {
+  return num.toString().slice(-1);
+}
+
+console.log(`The last digit of 42 is ${getLastDigit(42)}`);
+console.log(`The last digit of 105 is ${getLastDigit(105)}`);
+console.log(`The last digit of 806 is ${getLastDigit(806)}`);
 
 // This program should tell the user the last digit of each number.
 // Explain why getLastDigit is not working properly - correct the problem
diff --git a/Sprint-3/3-mandatory-implement/1-bmi.js b/Sprint-3/3-mandatory-implement/1-bmi.js
index 58b1085f1..93b6a2e1c 100644
--- a/Sprint-3/3-mandatory-implement/1-bmi.js
+++ b/Sprint-3/3-mandatory-implement/1-bmi.js
@@ -16,4 +16,6 @@
 
 function calculateBMI(weight, height) {
   // return the BMI of someone based off their weight and height
+  const bmi = weight / (height * height);
+  return bmi.toFixed(1);
 }
diff --git a/Sprint-3/3-mandatory-implement/2-cases.js b/Sprint-3/3-mandatory-implement/2-cases.js
index 5b0ef77ad..1bb0a5b72 100644
--- a/Sprint-3/3-mandatory-implement/2-cases.js
+++ b/Sprint-3/3-mandatory-implement/2-cases.js
@@ -14,3 +14,6 @@
 // You will need to come up with an appropriate name for the function
 // Use the MDN string documentation to help you find a solution
 // This might help https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase
+function toUpperSnakeCase(str) { 
+  return str.toUpperCase().replaceAll(" ", "_");
+}
diff --git a/Sprint-3/3-mandatory-implement/3-to-pounds.js b/Sprint-3/3-mandatory-implement/3-to-pounds.js
index 10754da73..c1b79c939 100644
--- a/Sprint-3/3-mandatory-implement/3-to-pounds.js
+++ b/Sprint-3/3-mandatory-implement/3-to-pounds.js
@@ -4,3 +4,27 @@
 // You will need to declare a function called toPounds with an appropriately named parameter.
 
 // You should call this function a number of times to check it works for different inputs
+
+function toPounds(penceString) {
+  
+  const penceStringWithoutTrailingP = penceString.substring(
+    0,
+    penceString.length - 1
+  );
+  const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+  const pounds = paddedPenceNumberString.substring(
+    0,
+    paddedPenceNumberString.length - 2
+  );
+  const pence = paddedPenceNumberString
+    .substring(paddedPenceNumberString.length - 2)
+    .padEnd(2, "0");
+  
+  return `£${pounds}.${pence}`;
+}
+
+
+console.log(toPounds("399p")); 
+console.log(toPounds("50p"));  
+console.log(toPounds("5p"));   
+console.log(toPounds("1250p"));
diff --git a/Sprint-3/4-mandatory-interpret/time-format.js b/Sprint-3/4-mandatory-interpret/time-format.js
index c0dd9c9a5..21dbd48f0 100644
--- a/Sprint-3/4-mandatory-interpret/time-format.js
+++ b/Sprint-3/4-mandatory-interpret/time-format.js
@@ -22,17 +22,30 @@ function formatTimeDisplay(seconds) {
 
 // a) When formatTimeDisplay is called how many times will pad be called?
 // =============> write your answer here
+// 3
 
 // Call formatTimeDisplay with an input of 61, now answer the following:
 
 // b) What is the value assigned to num when pad is called for the first time?
 // =============> write your answer here
+// num = 0
 
 // c) What is the return value of pad when it is called for the first time?
 // =============> write your answer here
+// "00"
 
 // d) What is the value assigned to num when pad is called for the last time in this program?  Explain your answer
 // =============> write your answer here
+// num = 1
+// The three calls are:
+// pad(totalHours)       -> pad(0)
+// pad(remainingMinutes) -> pad(1)
+// pad(remainingSeconds) -> pad(1)
+// Therefore, the last call receives 1 as num.
 
 // e) What is the return value of pad when it is called for the last time in this program?  Explain your answer
 // =============> write your answer here
+// "01"
+// num is 1, so numString starts as "1".
+// Because its length is less than 2, "0" is added to the beginning.
+// The function returns "01".