diff --git a/Sprint-2/1-key-errors/0.js b/Sprint-2/1-key-errors/0.js
index 653d6f5a07..dc0c6d31d5 100644
--- a/Sprint-2/1-key-errors/0.js
+++ b/Sprint-2/1-key-errors/0.js
@@ -1,13 +1,22 @@
 // Predict and explain first...
 //  =============> write your prediction here
+//I predict this code will take the first letter of the string and capitalise it.
 
 // 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
+//The syntax error happens because variable str is declared twice.
+
 // =============> write your new code here
+function capitalise(str) {
+  let capitalisedStr = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return capitalisedStr;
+}
+console.log(capitalise("hello"));
+console.log(capitalise("how are you?"));
diff --git a/Sprint-2/1-key-errors/1.js b/Sprint-2/1-key-errors/1.js
index f2d56151f4..d961fef0bf 100644
--- a/Sprint-2/1-key-errors/1.js
+++ b/Sprint-2/1-key-errors/1.js
@@ -2,19 +2,29 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
+/*When this program runs, there will be two errors: the function redeclares decimalNumber,
+and decimalNumber is used in console.log even though it is not defined outside the function.*/
 
 // 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
+// When I run this code, I get a SyntaxError because decimalNumber is already declared inside the function.
 
 // 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));
+console.log(convertToPercentage(0.45));
diff --git a/Sprint-2/1-key-errors/2.js b/Sprint-2/1-key-errors/2.js
index aad57f7cfe..a77ebbc4ec 100644
--- a/Sprint-2/1-key-errors/2.js
+++ b/Sprint-2/1-key-errors/2.js
@@ -1,20 +1,25 @@
-
 // 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 think the problem in this code is the parameter inside the function. A number cannot be used as a parameter name.
 
-function square(3) {
+/*function square(3) {
     return num * num;
-}
+}*/
 
 // =============> write the error message here
+//SyntaxError: Unexpected number
 
 // =============> explain this error message here
+//The error message means that number cannot be used as a parameter name.
 
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
-
-
+function square(num) {
+  return num * num;
+}
+console.log(square(2));
+console.log(square(3));
diff --git a/Sprint-2/2-mandatory-debug/0.js b/Sprint-2/2-mandatory-debug/0.js
index b27511b417..3641f4a187 100644
--- a/Sprint-2/2-mandatory-debug/0.js
+++ b/Sprint-2/2-mandatory-debug/0.js
@@ -1,14 +1,22 @@
 // Predict and explain first...
 
 // =============> write your prediction here
+//I think this code will not show the correct result because the function logs the answer instead of returning it.
 
-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)}`);
+console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);*/
 
 // =============> write your explanation here
+/*First, the function multiplies 10 and 32 and prints the result. However, in the second console.log 
+the value becomes undefined because the function does not return anything, so the template string 
+receives undefined instead of the number.*/
 
 // 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-2/2-mandatory-debug/1.js b/Sprint-2/2-mandatory-debug/1.js
index 37cedfbcfd..4512b6855a 100644
--- a/Sprint-2/2-mandatory-debug/1.js
+++ b/Sprint-2/2-mandatory-debug/1.js
@@ -1,13 +1,22 @@
 // Predict and explain first...
 //  =============> write your prediction here
+//I think this code will not give correct output, it will give undefined.
 
-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
+/*This code will print undefined because return; stops the function immediately.
+ The line a + b is never executed, so the function returns undefined and the template 
+ string receives undefined instead of the sum.*/
+
 // 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-2/2-mandatory-debug/2.js b/Sprint-2/2-mandatory-debug/2.js
index 57d3f5dc35..9f0a53e259 100644
--- a/Sprint-2/2-mandatory-debug/2.js
+++ b/Sprint-2/2-mandatory-debug/2.js
@@ -2,8 +2,9 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+//I think all three console.logs will output 3 because the function always uses the global variable.
 
-const num = 103;
+/*const num = 103;
 
 function getLastDigit() {
   return num.toString().slice(-1);
@@ -11,14 +12,29 @@ 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 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 output is the way it is because the variable num (103) is declared 
+in the global scope. The function getLastDigit always uses this global variable
+ instead of the argument passed in, so it always returns the last digit of 103, which is 3.*/
+
 // 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 103 is ${getLastDigit(103)}`);
+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-2/3-mandatory-implement/1-bmi.js b/Sprint-2/3-mandatory-implement/1-bmi.js
index 17b1cbde1b..b06d752af0 100644
--- a/Sprint-2/3-mandatory-implement/1-bmi.js
+++ b/Sprint-2/3-mandatory-implement/1-bmi.js
@@ -15,5 +15,7 @@
 // It should return their Body Mass Index to 1 decimal place
 
 function calculateBMI(weight, height) {
-    // return the BMI of someone based off their weight and height
-}
\ No newline at end of file
+  let bmi = weight / (height * height);
+  return bmi.toFixed(1);
+}
+console.log(calculateBMI(70, 1.73));
diff --git a/Sprint-2/3-mandatory-implement/2-cases.js b/Sprint-2/3-mandatory-implement/2-cases.js
index 5b0ef77ad9..4d4a38592c 100644
--- a/Sprint-2/3-mandatory-implement/2-cases.js
+++ b/Sprint-2/3-mandatory-implement/2-cases.js
@@ -14,3 +14,9 @@
 // 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 snakeCase(str) {
+  return str.toUpperCase().replace(/ /g, "_");
+}
+console.log(snakeCase("hello there"));
+console.log(snakeCase("a b c d"));
diff --git a/Sprint-2/3-mandatory-implement/3-to-pounds.js b/Sprint-2/3-mandatory-implement/3-to-pounds.js
index 6265a1a703..f746ca479f 100644
--- a/Sprint-2/3-mandatory-implement/3-to-pounds.js
+++ b/Sprint-2/3-mandatory-implement/3-to-pounds.js
@@ -4,3 +4,25 @@
 // 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("5p"));
+console.log(toPounds("50p"));
+console.log(toPounds("500p"));
diff --git a/Sprint-2/4-mandatory-interpret/time-format.js b/Sprint-2/4-mandatory-interpret/time-format.js
index 17127bc01e..fdb4c2df1d 100644
--- a/Sprint-2/4-mandatory-interpret/time-format.js
+++ b/Sprint-2/4-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
@@ -22,17 +23,30 @@ function formatTimeDisplay(seconds) {
 
 // a) When formatTimeDisplay is called how many times will pad be called?
 // =============> write your answer here
+//pad will be called 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
+// The value assigned to num when pad is called for the first time is 0.
 
 // c) What is the return value of pad is called for the first time?
 // =============> write your answer here
+// The return value of pad when it is called for the first time is "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
+// The value assigned to num when pad is called for the last time in this program is 1.
+// This is because the last call uses remainingSeconds, and for 61 seconds, remainingSeconds is 1.
 
 // 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 return value of pad when it is called for the last time in this program is "01".
+//This is because the last call is pad(1), and the pad function adds a zero in front to make it two digits.
+/*function pad(1) {
+  let numString = 1.toString(); // numString is "1"
+  while (numString.length < 2) { // numString.length is 1, so the loop runs
+    numString = "0" + numString; // numString becomes "01"
+    return numString; // returns "01"
+  }*/
diff --git a/Sprint-2/5-stretch-extend/format-time.js b/Sprint-2/5-stretch-extend/format-time.js
index 32a32e66b8..1aacb6f978 100644
--- a/Sprint-2/5-stretch-extend/format-time.js
+++ b/Sprint-2/5-stretch-extend/format-time.js
@@ -4,8 +4,15 @@
 
 function formatAs12HourClock(time) {
   const hours = Number(time.slice(0, 2));
+  const minutes = time.slice(3, 5);
   if (hours > 12) {
-    return `${hours - 12}:00 pm`;
+    return `${hours - 12}:${minutes} pm`;
+  }
+  if (hours === 12) {
+    return `12:${minutes} pm`;
+  }
+  if (hours === 0) {
+    return `12:${minutes} am`;
   }
   return `${time} am`;
 }
@@ -23,3 +30,39 @@ console.assert(
   currentOutput2 === 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("00:00");
+const targetOutput4 = "12:00 am";
+console.assert(
+  currentOutput4 === targetOutput4,
+  `current output: ${currentOutput4}, target output: ${targetOutput4}`
+);
+const currentOutput5 = formatAs12HourClock("00:30");
+const targetOutput5 = "12:30 am";
+console.assert(
+  currentOutput5 === targetOutput5,
+  `current output: ${currentOutput5}, target output: ${targetOutput5}`
+);
+const currentOutput6 = formatAs12HourClock("12:35");
+const targetOutput6 = "12:35 pm";
+console.assert(
+  currentOutput6 === targetOutput6,
+  `current output: ${currentOutput6}, target output: ${targetOutput6}`
+);
+const currentOutput7 = formatAs12HourClock("01:01");
+const targetOutput7 = "01:01 am";
+console.assert(
+  currentOutput7 === targetOutput7,
+  `current output: ${currentOutput7}, target output: ${targetOutput7}`
+);
+const currentOutput8 = formatAs12HourClock("13:01");
+const targetOutput8 = "1:01 pm";
+console.assert(
+  currentOutput8 === targetOutput8,
+  `current output: ${currentOutput8}, target output: ${targetOutput8}`
+);