diff --git a/Sprint-3/1-key-errors/0.js b/Sprint-3/1-key-errors/0.js
index 653d6f5a0..e11446e2e 100644
--- a/Sprint-3/1-key-errors/0.js
+++ b/Sprint-3/1-key-errors/0.js
@@ -1,13 +1,25 @@
 // Predict and explain first...
-//  =============> write your prediction here
+//  =============>// I predict JavaScript will give a SyntaxError because str is declared twice in the function.
 
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
 
-function capitalise(str) {
+/*function capitalise(str) {
   let str = `${str[0].toUpperCase()}${str.slice(1)}`;
   return str;
 }
-
-// =============> write your explanation here
+capitalise("hello");*/
+/* =============>  The error happens because str is already the function's parameter.
+   let str tries to use the same name again, so JavaScript gives a SyntaxError.
+   The function stops before it can run. */
 // =============> write your new code here
+function capitalise(str) {
+  if (str === "") {
+    return "";
+  }
+
+  const result = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return result;
+}
+
+console.log(`Result: "${capitalise("")}"`);
diff --git a/Sprint-3/1-key-errors/1.js b/Sprint-3/1-key-errors/1.js
index f2d56151f..9fb514925 100644
--- a/Sprint-3/1-key-errors/1.js
+++ b/Sprint-3/1-key-errors/1.js
@@ -1,20 +1,29 @@
 // Predict and explain first...
 
 // Why will an error occur when this program runs?
-// =============> write your prediction here
+// =============>// I predict a SyntaxError because decimalNumber is declared as a parameter and then declared again with const.
 
 // Try playing computer with the example to work out what is going on
 
-function convertToPercentage(decimalNumber) {
+/*function convertToPercentage(decimalNumber) {
   const decimalNumber = 0.5;
   const percentage = `${decimalNumber * 100}%`;
 
   return percentage;
 }
 
-console.log(decimalNumber);
+console.log(decimalNumber);*/
 
-// =============> write your explanation here
+/* =============>  decimalNumber is already the function parameter.
+   const decimalNumber tries to declare the same name again inside the function,
+   so JavaScript gives a SyntaxError. */
 
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function convertToPercentage(decimalNumber) {
+  const percentage = `${(decimalNumber * 100).toFixed(1)}%`;
+
+  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..042368fa6 100644
--- a/Sprint-3/1-key-errors/2.js
+++ b/Sprint-3/1-key-errors/2.js
@@ -1,20 +1,21 @@
-
 // Predict and explain first BEFORE you run any code...
 
 // this function should square any number but instead we're going to get an error
 
-// =============> write your prediction of the error here
+// =============> // I predict a SyntaxError because 3 is a number, but a function parameter needs to be a name.
 
-function square(3) {
+/*function square(3) {
     return num * num;
 }
+*/
+// =============> SyntaxError: Unexpected number
 
-// =============> write the error message here
-
-// =============> explain this error message here
+// =============> The error happens because 3 is not a name. A parameter needs a name, like num.
 
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
-
-
+function square(num) {
+  return num * num;
+}
+console.log(square(3));
diff --git a/Sprint-3/2-mandatory-debug/0.js b/Sprint-3/2-mandatory-debug/0.js
index b27511b41..1661caf95 100644
--- a/Sprint-3/2-mandatory-debug/0.js
+++ b/Sprint-3/2-mandatory-debug/0.js
@@ -1,14 +1,18 @@
 // Predict and explain first...
 
-// =============> write your prediction here
+// =============> I couldn't predict until I run the code
 
-function multiply(a, b) {
+/*function multiply(a, b) {
   console.log(a * b);
 }
 
-console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
-
-// =============> write your explanation here
+console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);*/
 
+/* =============> The Terminal gives an answer of 320 but also says "The result of multiplying 10 and 32 is undefined"
+which makes me think that the function has no return so it gives back 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..0d7d597b5 100644
--- a/Sprint-3/2-mandatory-debug/1.js
+++ b/Sprint-3/2-mandatory-debug/1.js
@@ -1,13 +1,19 @@
 // Predict and explain first...
-//  =============> write your prediction here
+//  =============> I predict the code won't work because there's a ";" after return.
 
-function sum(a, b) {
+/*function sum(a, b) {
   return;
   a + b;
 }
 
-console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
+console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);*/
 
-// =============> write your explanation here
+/* =============> The sum is undefined because the semicolon after return ends it too early, 
+the function returns before adding a and b.*/
 // 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..5f4ce680b 100644
--- a/Sprint-3/2-mandatory-debug/2.js
+++ b/Sprint-3/2-mandatory-debug/2.js
@@ -1,9 +1,9 @@
 // Predict and explain first...
 
 // Predict the output of the following code:
-// =============> Write your prediction here
+// =============> I predict the result will be wrong because the num is set set on 103.
 
-const num = 103;
+/*const num = 103;
 
 function getLastDigit() {
   return num.toString().slice(-1);
@@ -11,14 +11,33 @@ function getLastDigit() {
 
 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)}`);
+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 output:
+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
+/* =============> The problem is that the function ignores the numbers passed to it, 
+ it always uses num, which is 103, so it returns 3 every time.*/
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+/*function getLastDigit() {
+  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
+// In this case getLastDigit is not working because it's parameter is empty and not declared.
+// Here's the right code:
+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)}`);
diff --git a/Sprint-3/3-mandatory-implement/1-bmi.js b/Sprint-3/3-mandatory-implement/1-bmi.js
index 58b1085f1..ba8f010d1 100644
--- a/Sprint-3/3-mandatory-implement/1-bmi.js
+++ b/Sprint-3/3-mandatory-implement/1-bmi.js
@@ -15,5 +15,6 @@
 // It should return a string of their Body Mass Index to 1 decimal place
 
 function calculateBMI(weight, height) {
-  // return the BMI of someone based off their weight and height
+  return (weight / (height * height)).toFixed(1);
 }
+console.log(calculateBMI(52, 1.63));
diff --git a/Sprint-3/3-mandatory-implement/2-cases.js b/Sprint-3/3-mandatory-implement/2-cases.js
index 5b0ef77ad..574482364 100644
--- a/Sprint-3/3-mandatory-implement/2-cases.js
+++ b/Sprint-3/3-mandatory-implement/2-cases.js
@@ -14,3 +14,8 @@
 // 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(words) {
+  return words.toUpperCase().trim().split(/\s+/).join("_");
+}
+
+console.log(toUpperSnakeCase("hello there"));
diff --git a/Sprint-3/3-mandatory-implement/3-to-pounds.js b/Sprint-3/3-mandatory-implement/3-to-pounds.js
index 10754da73..8562c5843 100644
--- a/Sprint-3/3-mandatory-implement/3-to-pounds.js
+++ b/Sprint-3/3-mandatory-implement/3-to-pounds.js
@@ -4,3 +4,20 @@
 // 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 penceNumberString = String(penceString).replace(/p$/i, "");
+  const paddedPenceNumberString = penceNumberString.padStart(3, "0");
+
+  const pounds = paddedPenceNumberString.substring(
+    0,
+    paddedPenceNumberString.length - 2,
+  );
+
+  const pence = paddedPenceNumberString
+    .substring(paddedPenceNumberString.length - 2)
+    .padEnd(2, "0");
+  return `£${pounds}.${pence}`;
+}
+console.log(toPounds("599p"));
+console.log(toPounds("6p"));
+console.log(toPounds("2568p"));
diff --git a/Sprint-3/4-mandatory-interpret/time-format.js b/Sprint-3/4-mandatory-interpret/time-format.js
index c0dd9c9a5..be7bd335e 100644
--- a/Sprint-3/4-mandatory-interpret/time-format.js
+++ b/Sprint-3/4-mandatory-interpret/time-format.js
@@ -14,6 +14,7 @@ function formatTimeDisplay(seconds) {
 
   return `${pad(totalHours)}:${pad(remainingMinutes)}:${pad(remainingSeconds)}`;
 }
+console.log(formatTimeDisplay(61));
 
 // You will need to play computer with this example - use the Python Visualiser https://pythontutor.com/visualize.html#mode=edit
 // to help you answer these questions
@@ -21,18 +22,17 @@ function formatTimeDisplay(seconds) {
 // Questions
 
 // a) When formatTimeDisplay is called how many times will pad be called?
-// =============> write your answer here
+// =============>Pad will be called 3 times: once for hours, once for minutes, and once for seconds.
 
 // 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
+// =============> the first time pad is called, num gets the value of totalHours, which is 0.
 
 // c) What is the return value of pad when it is called for the first time?
-// =============> write your answer here
-
+// =============> the first time pad is called, it returns 00 because num is 0 and pad adds a zero in front.
 // 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
+// =============> the last time pad is called, num is 1 because there is 1 second left.
 
 // 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
+// =============>the last time pad is called, it returns 01 because num is 1 and pad adds a 0 in front.
diff --git a/Sprint-3/5-stretch-extend/format-time.js b/Sprint-3/5-stretch-extend/format-time.js
index 32a32e66b..b6914afaf 100644
--- a/Sprint-3/5-stretch-extend/format-time.js
+++ b/Sprint-3/5-stretch-extend/format-time.js
@@ -3,23 +3,49 @@
 // Your task is to write tests for as many different groups of input data or edge cases as you can, and fix any bugs you find.
 
 function formatAs12HourClock(time) {
-  const hours = Number(time.slice(0, 2));
-  if (hours > 12) {
-    return `${hours - 12}:00 pm`;
+  const [hoursString, minutesString = "00"] = time.split(":");
+  const hours = Number(hoursString);
+  const minutes = minutesString.padStart(2, "0");
+
+  let suffix = "am";
+  if (hours >= 12) {
+    suffix = "pm";
   }
-  return `${time} am`;
-}
 
-const currentOutput = formatAs12HourClock("08:00");
-const targetOutput = "08:00 am";
-console.assert(
-  currentOutput === targetOutput,
-  `current output: ${currentOutput}, target output: ${targetOutput}`
-);
+  let formattedHours = hours % 12;
+  if (formattedHours === 0) {
+    formattedHours = 12;
+  }
+
+  return `${formattedHours}:${minutes} ${suffix}`;
+}
 
 const currentOutput2 = formatAs12HourClock("23:00");
 const targetOutput2 = "11:00 pm";
 console.assert(
   currentOutput2 === targetOutput2,
-  `current output: ${currentOutput2}, target output: ${targetOutput2}`
+  `current output: ${currentOutput2}, target output: ${targetOutput2}`,
 );
+
+const noonOutput = formatAs12HourClock("12:00");
+const noonTarget = "12:00 pm";
+console.assert(
+  noonOutput === noonTarget,
+  `current output: ${noonOutput}, target output: ${noonTarget}`,
+);
+
+const midnightOutput = formatAs12HourClock("00:00");
+const midnightTarget = "12:00 am";
+console.assert(
+  midnightOutput === midnightTarget,
+  `current output: ${midnightOutput}, target output: ${midnightTarget}`,
+);
+
+const singleDigitMinuteOutput = formatAs12HourClock("9:5");
+const singleDigitMinuteTarget = "9:05 am";
+console.assert(
+  singleDigitMinuteOutput === singleDigitMinuteTarget,
+  `current output: ${singleDigitMinuteOutput}, target output: ${singleDigitMinuteTarget}`,
+);
+
+console.log("All formatAs12HourClock tests passed.");