diff --git a/Sprint-3/1-key-errors/0.js b/Sprint-3/1-key-errors/0.js
index 653d6f5a0..b231fac70 100644
--- a/Sprint-3/1-key-errors/0.js
+++ b/Sprint-3/1-key-errors/0.js
@@ -1,13 +1,21 @@
 // Predict and explain first...
-//  =============> write your prediction here
+//  function parameter and variable inside the function have same name.
 
 // call the function capitalise with a string input
+console.log(capitalise("message"));
 // 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;
-}
+/*Identifier 'str' has already been declared . 
+This mean that 'str' has already been declared as a function parameter,
+so we cannot declare another variable with the same name using 'let'.
+ */
 
 // =============> write your explanation here
+// The error occurs because 'str' is already declare as a function parameter.
+//The 'let str' inside the function tries to declare 'str' again in the same scope.
+//I changed the name of new variable to 'result' to fix the error.
+
 // =============> write your new code here
+function capitalise(str) {
+  let result = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return result;
+}
diff --git a/Sprint-3/1-key-errors/1.js b/Sprint-3/1-key-errors/1.js
index f2d56151f..2d15e8022 100644
--- a/Sprint-3/1-key-errors/1.js
+++ b/Sprint-3/1-key-errors/1.js
@@ -2,19 +2,27 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
-
+// If we run the program, I predict we will get an error.
+// The first problem is that 'decimalNumber' is already function parameter, but you try to declare another variable with the same name inside the function.
+//another problem is that 'decimalNumber' is a local variable inside the function
+// and we cannot access to it outside the function.
+//------------------------------------------------------
 // Try playing computer with the example to work out what is going on
+//SyntaxError: Identifier 'decimalNumber' has already been declared
+
+// =============> write your explanation here
+
+// The error occurs because 'decimalNumber' has already been declared
+// as a function parameter. we cannot declare it again with 'const'
+
+// Finally, correct the code to fix the problem
+// =============> write your new code here
+const decimalNumber = 0.5;
 
 function convertToPercentage(decimalNumber) {
-  const decimalNumber = 0.5;
   const percentage = `${decimalNumber * 100}%`;
 
   return percentage;
 }
 
-console.log(decimalNumber);
-
-// =============> write your explanation here
-
-// Finally, correct the code to fix the problem
-// =============> write your new code here
+console.log(convertToPercentage(decimalNumber));
diff --git a/Sprint-3/1-key-errors/2.js b/Sprint-3/1-key-errors/2.js
index aad57f7cf..15c5512b8 100644
--- a/Sprint-3/1-key-errors/2.js
+++ b/Sprint-3/1-key-errors/2.js
@@ -1,20 +1,27 @@
-
 // Predict and explain first BEFORE you run any code...
+// when we run the code, I predict that we will got the error in function argument
+//because it is not a variable
 
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
+//
 
-function square(3) {
+/*function square(3) {
     return num * num;
-}
+}*/
 
 // =============> write the error message here
+// SyntaxError: Unexpected number
 
 // =============> explain this error message here
+// The error occurs because 3 is a number, not a valid variable name.
 
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
-
-
+const num = 3;
+function square(num) {
+  return num * num;
+}
+console.log(square(num));
diff --git a/Sprint-3/2-mandatory-debug/0.js b/Sprint-3/2-mandatory-debug/0.js
index b27511b41..e3bc4d83d 100644
--- a/Sprint-3/2-mandatory-debug/0.js
+++ b/Sprint-3/2-mandatory-debug/0.js
@@ -1,14 +1,24 @@
 // Predict and explain first...
-
 // =============> write your prediction here
+//when we run the code, I predict that the function  just execute but doesn't return any thing.
+// function just print the result of multiply
+// I am not sure what going to be show in the second console.log
 
-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
+// After running the code, the multiply function display the result (320)
+// but it does not return result back to the code
+// therefore, multiply(10, 32) evaluate 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..00cbe2bc2 100644
--- a/Sprint-3/2-mandatory-debug/1.js
+++ b/Sprint-3/2-mandatory-debug/1.js
@@ -1,13 +1,21 @@
 // Predict and explain first...
-//  =============> write your prediction here
+//  =============> I think the position of return inside the function is wrong
+//probably it is show nothing
 
-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
+// After running code it is show "The sum of 10 and 32 is undefined"
+// because return has no value so it return 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)}`);
diff --git a/Sprint-3/2-mandatory-debug/2.js b/Sprint-3/2-mandatory-debug/2.js
index 57d3f5dc3..54fa3df0b 100644
--- a/Sprint-3/2-mandatory-debug/2.js
+++ b/Sprint-3/2-mandatory-debug/2.js
@@ -1,9 +1,11 @@
 // Predict and explain first...
+// In my idea we can not change value of num as it is defined by const
 
 // Predict the output of the following code:
 // =============> Write your prediction here
+//perhaps we will get value definition error
 
-const num = 103;
+/*const num = 103;
 
 function getLastDigit() {
   return num.toString().slice(-1);
@@ -11,14 +13,26 @@ 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
+// I was wrong in all the function call, the result is the same because the function always uses the global num.
+
 // 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..f5c1ce957 100644
--- a/Sprint-3/3-mandatory-implement/1-bmi.js
+++ b/Sprint-3/3-mandatory-implement/1-bmi.js
@@ -15,5 +15,7 @@
 // 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 BMI = weight / (height * height);
+  return BMI.toFixed(1);
 }
+console.log(`your body mass is ${calculateBMI(87, 1.58)}`);
diff --git a/Sprint-3/3-mandatory-implement/2-cases.js b/Sprint-3/3-mandatory-implement/2-cases.js
index 5b0ef77ad..587eea086 100644
--- a/Sprint-3/3-mandatory-implement/2-cases.js
+++ b/Sprint-3/3-mandatory-implement/2-cases.js
@@ -14,3 +14,13 @@
 // 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(text) {
+  const newText = text.replace(/ /g, "_");
+  return newText.toUpperCase();
+}
+console.log(
+  `The upper snake case of "hello there" is ${toUpperSnakeCase("hello there")}`,
+);
+console.log(
+  `The upper snake case of "lord of rings" is ${toUpperSnakeCase("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..84b875e51 100644
--- a/Sprint-3/3-mandatory-implement/3-to-pounds.js
+++ b/Sprint-3/3-mandatory-implement/3-to-pounds.js
@@ -4,3 +4,23 @@
 // 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("2p"));
+console.log(toPounds("4500p"));
+console.log(toPounds("95p"));
+console.log(toPounds("3675p"));
diff --git a/Sprint-3/4-mandatory-interpret/time-format.js b/Sprint-3/4-mandatory-interpret/time-format.js
index c0dd9c9a5..657377776 100644
--- a/Sprint-3/4-mandatory-interpret/time-format.js
+++ b/Sprint-3/4-mandatory-interpret/time-format.js
@@ -14,25 +14,28 @@ 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
+// =============> The pad function is called three times on line 15.
 
 // 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 is 0.
 
 // c) What is the return value of pad when it is called for the first time?
-// =============> write your answer here
+// =============> The value of pad when it is called for the first time "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 assign to num is 1.
+//  because the last call to pad is pad(remainingSeconds), and remainingSeconds is 1
+// when formatTimeDisplay(61) is called.
 
 // 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 is "01" because the last call to pad is pad(1).
+// The pad function add a zero to make the number two digits.
diff --git a/Sprint-3/5-stretch-extend/format-time.js b/Sprint-3/5-stretch-extend/format-time.js
index 32a32e66b..7bc4b34a9 100644
--- a/Sprint-3/5-stretch-extend/format-time.js
+++ b/Sprint-3/5-stretch-extend/format-time.js
@@ -4,22 +4,56 @@
 
 function formatAs12HourClock(time) {
   const hours = Number(time.slice(0, 2));
+  if (hours === 0) {
+    return `12${time.slice(2)} am`;
+  }
+  if (hours === 12) {
+    return `12${time.slice(2)} pm`;
+  }
   if (hours > 12) {
-    return `${hours - 12}:00 pm`;
+    return `${String(hours - 12).padStart(2, "0")}:${time.slice(3)} pm `;
   }
   return `${time} am`;
 }
 
-const currentOutput = formatAs12HourClock("08:00");
-const targetOutput = "08:00 am";
+const currentOutput = formatAs12HourClock("08:30");
+const targetOutput = "08:30 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";
+const currentOutput2 = formatAs12HourClock("15:30");
+const targetOutput2 = "03:30 pm";
 console.assert(
   currentOutput2 === targetOutput2,
-  `current output: ${currentOutput2}, target output: ${targetOutput2}`
+  `current output: ${currentOutput2}, target output: ${targetOutput2}`,
 );
+
+const currentOutput5 = formatAs12HourClock("11:59");
+const targetOutput5 = "11:59 am";
+console.assert(
+  currentOutput5 === targetOutput5,
+  `current output: ${currentOutput5}, target output: ${targetOutput5}`,
+);
+
+const currentOutput3 = formatAs12HourClock("00:00");
+const targetOutput3 = "12:00 am";
+
+console.assert(
+  currentOutput3 === targetOutput3,
+  `current output: ${currentOutput3}, target output: ${targetOutput3}`,
+);
+const currentOutput4 = formatAs12HourClock("12:02");
+const targetOutput4 = "12:02 pm";
+
+console.assert(
+  currentOutput4 === targetOutput4,
+  `current output: ${currentOutput4}, target output: ${targetOutput4}`,
+);
+
+console.log(currentOutput, targetOutput);
+console.log(currentOutput2, targetOutput2);
+console.log(currentOutput3, targetOutput3);
+console.log(currentOutput4, targetOutput4);
+console.log(currentOutput5, targetOutput5);