diff --git a/Sprint-3/1-key-errors/0.js b/Sprint-3/1-key-errors/0.js
index 653d6f5a0..5c67fecee 100644
--- a/Sprint-3/1-key-errors/0.js
+++ b/Sprint-3/1-key-errors/0.js
@@ -1,13 +1,22 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// when user input the string. First index will be capitalised.
 
 // 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;
+//}
+
+// =============> write your explanation here
+// SyntaxError: Identifier 'str' has already been declared. "str" has been declared in function. In the local scope of original code, str declared again.
+//It caused the problem of redeclaration. Delete the "let" in local scope
+// =============> write your new code here
 function capitalise(str) {
-  let str = `${str[0].toUpperCase()}${str.slice(1)}`;
+  str = `${str[0].toUpperCase()}${str.slice(1)}`;
   return str;
 }
 
-// =============> write your explanation here
-// =============> write your new code here
+console.log(capitalise("roger"));
diff --git a/Sprint-3/1-key-errors/1.js b/Sprint-3/1-key-errors/1.js
index f2d56151f..64cc0dbae 100644
--- a/Sprint-3/1-key-errors/1.js
+++ b/Sprint-3/1-key-errors/1.js
@@ -2,19 +2,31 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
+// There have the problem of redeclaration of the statement of decimalNumber. Local Scope should return to decimalNumber instead.
+// To print the code, the code should be console.log(decimalNumber)
 
 // Try playing computer with the example to work out what is going on
 
-function convertToPercentage(decimalNumber) {
-  const decimalNumber = 0.5;
-  const percentage = `${decimalNumber * 100}%`;
+//function convertToPercentage(decimalNumber) {
+//  const decimalNumber = 0.5;
+//  const percentage = `${decimalNumber * 100}%`;
 
-  return percentage;
-}
+//  return percentage;
 
-console.log(decimalNumber);
+//console.log(decimalNumber);
 
 // =============> write your explanation here
+// In the local scope, remove "const decimalNumber = 0.5". for the second line of local scope, 'const percentage' should be change to
+//'decimalNumber' to avoid redeclaration and refer the correct variable. and return the function to 'decimalNumber'
+//finally console.log(convertToPercentage(0.5)) should be used to print the function.
 
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+
+function convertToPercentage(decimalNumber) {
+  decimalNumber = `${decimalNumber * 100}%`;
+
+  return decimalNumber;
+}
+
+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..290e0656c 100644
--- a/Sprint-3/1-key-errors/2.js
+++ b/Sprint-3/1-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
+// The code in local scope could not refer to variable. function square should attach with a variable instead of value.
 
-function square(3) {
-    return num * num;
-}
+//function square(3) {
+//    return num * num;
+//}
 
 // =============> write the error message here
+// SyntaxError: Unexpected number
 
 // =============> explain this error message here
+// =============> the error caused by the wrong input for the variable "square(3)".
 
 // 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..80fe37046 100644
--- a/Sprint-3/2-mandatory-debug/0.js
+++ b/Sprint-3/2-mandatory-debug/0.js
@@ -1,14 +1,23 @@
 // Predict and explain first...
 
 // =============> write your prediction here
+// A: The result of multiplying 10 and 32 is 320. But local scope code did not return to global.
 
-function multiply(a, b) {
-  console.log(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
+// The calculation of the a * b should apply the the statement (`The result of multiplying 10 and 32 is ${multiply(10, 32)}`).
+// because code on local scope did not return to global. The global cannot apply the result of local.
 
 // 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..0b584b5aa 100644
--- a/Sprint-3/2-mandatory-debug/1.js
+++ b/Sprint-3/2-mandatory-debug/1.js
@@ -1,13 +1,20 @@
 // Predict and explain first...
 //  =============> write your prediction here
+// The result of the function supposed to print 'The sum of 10 and 32 is 42' local scope should be return to sum.
 
-function sum(a, b) {
-  return;
-  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 answer is undefined because of local scope code did not return to global (sum). semicolon of return need to be removed.
 // 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..234392f74 100644
--- a/Sprint-3/2-mandatory-debug/2.js
+++ b/Sprint-3/2-mandatory-debug/2.js
@@ -2,23 +2,43 @@
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+// The function supposed to print the last digit of 42, 105 and 806 which is 2, 5, 6. But the function could not run smooth
+// because of the variable "num" has been declared.
 
-const num = 103;
+//const num = 103;
 
-function getLastDigit() {
-  return num.toString().slice(-1);
-}
+//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)}`);
+//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
 
 // 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
+// because num has been declared for 103 so the function could only return 3 even though use requested to return last digit of 42, 105, 806.
 // Finally, correct the code to fix the problem
 // =============> write your new code here
 
+function getLastDigit(number) {
+  return number.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
+// A: it is because num has been strictly declared as 103 before. and the value is console log could be be applied to function.
+// To fix this parameter of getLastDigit should assign for val as a placeholder to allow different value
diff --git a/Sprint-3/3-mandatory-implement/1-bmi.js b/Sprint-3/3-mandatory-implement/1-bmi.js
index 58b1085f1..ac5f071b3 100644
--- a/Sprint-3/3-mandatory-implement/1-bmi.js
+++ b/Sprint-3/3-mandatory-implement/1-bmi.js
@@ -15,5 +15,8 @@
 // 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
+  const rawBMI = weight / (height * height);
+  return rawBMI.toFixed(1);
 }
+
+console.log(calculateBMI(77, 1.83));
diff --git a/Sprint-3/3-mandatory-implement/2-cases.js b/Sprint-3/3-mandatory-implement/2-cases.js
index 5b0ef77ad..3031772b7 100644
--- a/Sprint-3/3-mandatory-implement/2-cases.js
+++ b/Sprint-3/3-mandatory-implement/2-cases.js
@@ -14,3 +14,11 @@
 // 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 upperSnakeCase(val) {
+  const upperCase = val.toUpperCase();
+  return upperCase.replaceAll(" ", "_");
+}
+
+console.log(upperSnakeCase("hello there"));
+console.log(upperSnakeCase("lord of the rings"));
diff --git a/Sprint-3/3-mandatory-implement/3-to-pounds.js b/Sprint-3/3-mandatory-implement/3-to-pounds.js
index 10754da73..ed39a3a56 100644
--- a/Sprint-3/3-mandatory-implement/3-to-pounds.js
+++ b/Sprint-3/3-mandatory-implement/3-to-pounds.js
@@ -4,3 +4,28 @@
 // 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("599p"));
+console.log(toPounds("1234p"));
+console.log(toPounds("49005p"));
+console.log(toPounds("789p"));
+console.log(toPounds("85p"));
diff --git a/Sprint-3/4-mandatory-interpret/time-format.js b/Sprint-3/4-mandatory-interpret/time-format.js
index c0dd9c9a5..6f8550e7b 100644
--- a/Sprint-3/4-mandatory-interpret/time-format.js
+++ b/Sprint-3/4-mandatory-interpret/time-format.js
@@ -15,24 +15,27 @@ 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
 
 // Questions
 
 // 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
+// =============> 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
+// =============> 1. The last calling of pad is pad(remainingSeconds).
 
 // 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". after pad(remainingSeconds) which is the last value returned.
+// 1 convert to "01" in function pad(num.)