diff --git a/Sprint-3/1-key-errors/0.js b/Sprint-3/1-key-errors/0.js
index 653d6f5a0..4170751bd 100644
--- a/Sprint-3/1-key-errors/0.js
+++ b/Sprint-3/1-key-errors/0.js
@@ -1,13 +1,28 @@
 // Predict and explain first...
 //  =============> write your prediction here
+//Answer: I predict that there will be a Reference Error, because str get's re-declared with let
+//inside the function even though it already is declared as it is the parameter. Perhaps it would
+// be solved by removing the "let".
 
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
 
+/*
 function capitalise(str) {
   let str = `${str[0].toUpperCase()}${str.slice(1)}`;
   return str;
 }
 
+console.log(capitalise("hellllo");
+*/
+
 // =============> write your explanation here
+// Answer: I got a Syntax Error, Identifier 'str' has already been declared. So 'str' needs to not
+// be declared again. I will try to write the code without the let
 // =============> write your new code here
+
+function capitalise(str) {
+  str = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return str;
+}
+console.log(capitalise("hellllo"));
diff --git a/Sprint-3/1-key-errors/1.js b/Sprint-3/1-key-errors/1.js
index f2d56151f..46997f2b9 100644
--- a/Sprint-3/1-key-errors/1.js
+++ b/Sprint-3/1-key-errors/1.js
@@ -2,9 +2,13 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
+// Answer: I will get a Syntax Error, because the variable decimalNumber is a parameter
+// of the function, and then it gets re-declared inside the function. Removing the
+// "const" would make sure it's not re-declared, just value reassigned on that line.
 
 // Try playing computer with the example to work out what is going on
 
+/*
 function convertToPercentage(decimalNumber) {
   const decimalNumber = 0.5;
   const percentage = `${decimalNumber * 100}%`;
@@ -13,8 +17,26 @@ function convertToPercentage(decimalNumber) {
 }
 
 console.log(decimalNumber);
+*/
 
 // =============> write your explanation here
+// Answer: I got SyntaxError: Identifier 'decimalNumber' has already been declared
+// I will make sure it's not re-declared in the function by removing the "const"
+
+// After removing the "const" I got a new error. ReferenceError: decimalNumber is not defined. I realized
+// that the console.log at the bottom didn't call the function but just logged decimalNumber which hadn't
+// been defined in the global scope. Putting back the "const", I will move the declaration of decimalNumber
+// to outside the function to make the scope global. Now the global decimalNumber has nothing to do with the
+// local parameter decimalNumber in the function.
 
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function convertToPercentage(decimalNumber) {
+  const percentage = `${decimalNumber * 100}%`;
+
+  return percentage;
+}
+
+const decimalNumber = 0.5;
+
+console.log(decimalNumber);
diff --git a/Sprint-3/1-key-errors/2.js b/Sprint-3/1-key-errors/2.js
index aad57f7cf..510e7a2c4 100644
--- a/Sprint-3/1-key-errors/2.js
+++ b/Sprint-3/1-key-errors/2.js
@@ -1,20 +1,38 @@
-
 // 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
+// Answer: I predict that we will get a Reference Error: num is not defined. Or perhaps an error about the 3, as
+// it is a number and therefore not a valid parameter name. I believe perhaps parameter names are like variable
+// names and can't start with a number.
 
+/*
 function square(3) {
     return num * num;
 }
+*/
 
 // =============> write the error message here
+// Answer: SyntaxError: Unexpected number
 
 // =============> explain this error message here
+// Answer: Yes we got an error message about the number 3. We wouldn't get a message about num not being defined
+// since the function isn't called in the code, so the inside of the function can't produce an error.
+// I will first try to update the 3 to n3, to see if it is a valid parameter name and see if the error goes away,
+// just as an experiment.
+
+// Answer: The error did go away. However it didn't solve our problem as we still want to receive 3 squared when
+// calling the function. I will change n3 to the proper parameter name, num. So it can be referenced inside the
+// function body. Then I will make a function call and pass in 3 there, as an argument to the parameter num.
+// Then I will log the result to see if it worked.
 
 // 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..966bab42c 100644
--- a/Sprint-3/2-mandatory-debug/0.js
+++ b/Sprint-3/2-mandatory-debug/0.js
@@ -1,14 +1,29 @@
 // Predict and explain first...
 
 // =============> write your prediction here
+// Answer: I predict the console will log first 320, and then on a new line "The result of multiplying 10 and 32 is ${NaN}"
+// This is because the function logs the result in it's body, so it will log it first as it is run, but
+// because it's not explicitly returning anything, it will just return NaN into the string literal logged at the end.
 
+/*
 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
+// Answer: In reality, I was almost correct, but the function returned undefined, not NaN, so it logged
+// 320, and then The result of multiplying 10 and 32 is undefined. Oh and also of course the string
+// interpolation brackets weren't included in the logged string like I had predicted.
+// I will fix the problem by returning a * b in the function body, instead of logging it.
 
 // 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..08bf5e52f 100644
--- a/Sprint-3/2-mandatory-debug/1.js
+++ b/Sprint-3/2-mandatory-debug/1.js
@@ -1,13 +1,30 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// Answer: I predict that what happens is `The sum of 10 and 32 is undefined` gets logged to the console.
+// That is because even though the function sum has a return statement, it doesn't return anything. There
+// is a value that is meant to be returned below the return statement, but because the function already returned
+// it will never reach that line in execution. That is why it is greyed out.
 
+/*
 function sum(a, b) {
   return;
   a + b;
 }
 
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);
+*/
 
 // =============> write your explanation here
+// Answer: Running the code logged "The sum of 10 and 32 is undefined" like I thought. I will fix the problem
+// by moving a + b; in the function body to be on the same line as return, so it gets returned instead of undefined.
+
 // 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)}`);
+
+// Answer: now "The sum of 10 and 32 is 42" is logged.
diff --git a/Sprint-3/2-mandatory-debug/2.js b/Sprint-3/2-mandatory-debug/2.js
index 57d3f5dc3..0639357bb 100644
--- a/Sprint-3/2-mandatory-debug/2.js
+++ b/Sprint-3/2-mandatory-debug/2.js
@@ -2,7 +2,11 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+// Answer: I believe that when we run the code we will get a Reference Error, because we are trying to
+// call a function getLastDigit with an argument even though the function doesn't have any parameters.
+// Or possibly the error might reference num in the function body being undefined.
 
+/*
 const num = 103;
 
 function getLastDigit() {
@@ -12,13 +16,46 @@ 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)}`);
+*/
 
 // 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
+// Answer: I was wrong, there was no error message. Instead
+// The last digit of 42 is 3
+// The last digit of 105 is 3
+// The last digit of 806 is 3
+// was logged to the console. There was no Reference Error about num being undefined in the function body
+// because num IS defined, just above the function and has global scope, so it is reachable by the function.
+// Also, no error was thrown due to calling the function with arguments even though it accepted no parameters.
+// This is because JavaScript is a dynamic/forgiving language that rather removes surplus information and keeps
+// executing the code than stops it and gives an error message. So any surplus arguments passed into a function
+// call just gets ignored. That is why the passed arguments have no effect on the function's return value.
+// To make them have effect, I will add a parameter to the function, and call it num. Then when num gets accessed
+// in the function body, it will not be the value of the global num, but instead the function-local parameter
+// num.
+
 // Finally, correct the code to fix the problem
 // =============> write your new code here
 
+const num = 103;
+
+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
+// Answer: now it works as expected
+// The last digit of 42 is 2
+// The last digit of 105 is 5
+// The last digit of 806 is 6
diff --git a/Sprint-3/3-mandatory-implement/1-bmi.js b/Sprint-3/3-mandatory-implement/1-bmi.js
index 58b1085f1..42b122752 100644
--- a/Sprint-3/3-mandatory-implement/1-bmi.js
+++ b/Sprint-3/3-mandatory-implement/1-bmi.js
@@ -15,5 +15,15 @@
 // 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 Number.parseFloat(weight / (height * height)).toFixed(1);
 }
+
+// Tests
+console.log(calculateBMI(55, 1.63));
+console.log(calculateBMI(120, 1.73));
+console.log(calculateBMI(80, 1.69));
+console.log(calculateBMI(51, 1.55));
+
+// Please could I have a little feedback about if I have refactored the function return too much?
+// And if so, what is a good guide on how many operations to perform in one line..? I can also
+// ask this in class if you prefer.
diff --git a/Sprint-3/3-mandatory-implement/2-cases.js b/Sprint-3/3-mandatory-implement/2-cases.js
index 5b0ef77ad..8d834bde9 100644
--- a/Sprint-3/3-mandatory-implement/2-cases.js
+++ b/Sprint-3/3-mandatory-implement/2-cases.js
@@ -14,3 +14,12 @@
 // 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().split(" ").join("_");
+}
+
+//tests
+console.log(toUpperSnakeCase("i want to scream"));
+console.log(toUpperSnakeCase("lord of the rings"));
+console.log(toUpperSnakeCase("This is a loud file name"));
diff --git a/Sprint-3/3-mandatory-implement/3-to-pounds.js b/Sprint-3/3-mandatory-implement/3-to-pounds.js
index 10754da73..725a0c73e 100644
--- a/Sprint-3/3-mandatory-implement/3-to-pounds.js
+++ b/Sprint-3/3-mandatory-implement/3-to-pounds.js
@@ -4,3 +4,32 @@
 // 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];
+}
+
+//tests
+let [pounds, pence] = toPounds("399p");
+console.log(`£${pounds}.${pence}`);
+[pounds, pence] = toPounds("3995p");
+console.log(`£${pounds}.${pence}`);
+[pounds, pence] = toPounds("42895p");
+console.log(`£${pounds}.${pence}`);
+[pounds, pence] = toPounds("2p");
+console.log(`£${pounds}.${pence}`);
diff --git a/Sprint-3/4-mandatory-interpret/time-format.js b/Sprint-3/4-mandatory-interpret/time-format.js
index c0dd9c9a5..39eaa8a60 100644
--- a/Sprint-3/4-mandatory-interpret/time-format.js
+++ b/Sprint-3/4-mandatory-interpret/time-format.js
@@ -21,18 +21,20 @@ function formatTimeDisplay(seconds) {
 // Questions
 
 // a) When formatTimeDisplay is called how many times will pad be called?
-// =============> write your answer here
+// Answer: 3 times
 
 // 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
+// Answer: 0
 
 // c) What is the return value of pad when it is called for the first time?
-// =============> write your answer here
+// Answer: "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
+// Answer: 1. Num is 1 in the last call to pad, because the argument sent into pad is remainingSeconds, which is
+// 1 because 1 is the remainder after dividing 61 with 60.
 
 // 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
+// Answer: "01". The return value is "01" because pad first turned 1 into a string "1", and then used a while loop
+// to concatenate (pad) zeros at the start of the "1" string until it became two in length.
diff --git a/Sprint-3/5-stretch-extend/format-time.js b/Sprint-3/5-stretch-extend/format-time.js
index 32a32e66b..126136c37 100644
--- a/Sprint-3/5-stretch-extend/format-time.js
+++ b/Sprint-3/5-stretch-extend/format-time.js
@@ -5,7 +5,9 @@
 function formatAs12HourClock(time) {
   const hours = Number(time.slice(0, 2));
   if (hours > 12) {
-    return `${hours - 12}:00 pm`;
+    return `${hours - 12 < 10 ? "0" : ""}${hours - 12}:${time.slice(-2)} pm`;
+  } else if (hours === 12) {
+    return `${time} pm`;
   }
   return `${time} am`;
 }
@@ -14,12 +16,40 @@ const currentOutput = formatAs12HourClock("08:00");
 const targetOutput = "08:00 am";
 console.assert(
   currentOutput === targetOutput,
-  `current output: ${currentOutput}, target output: ${targetOutput}`
+  `current output: ${currentOutput}, target output: ${targetOutput}`,
 );
 
 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 currentOutput3 = formatAs12HourClock("12:00");
+const targetOutput3 = "12:00 pm";
+console.assert(
+  currentOutput3 === targetOutput3,
+  `current output: ${currentOutput3}, target output: ${targetOutput3}`,
+);
+
+const currentOutput4 = formatAs12HourClock("15:45");
+const targetOutput4 = "03:45 pm";
+console.assert(
+  currentOutput4 === targetOutput4,
+  `current output: ${currentOutput4}, target output: ${targetOutput4}`,
+);
+
+const currentOutput5 = formatAs12HourClock("08:25");
+const targetOutput5 = "08:25 am";
+console.assert(
+  currentOutput5 === targetOutput5,
+  `current output: ${currentOutput5}, target output: ${targetOutput5}`,
+);
+
+const currentOutput6 = formatAs12HourClock("12:17");
+const targetOutput6 = "12:17 pm";
+console.assert(
+  currentOutput6 === targetOutput6,
+  `current output: ${currentOutput6}, target output: ${targetOutput6}`,
 );