diff --git a/Sprint-3/1-key-errors/0.js b/Sprint-3/1-key-errors/0.js
index 653d6f5a0..552605d40 100644
--- a/Sprint-3/1-key-errors/0.js
+++ b/Sprint-3/1-key-errors/0.js
@@ -1,13 +1,12 @@
 // Predict and explain first...
-//  =============> write your prediction here
+//  =============> I expect the function capitalise will turn first letter of string given by user into capital letter.
 
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
 
+// =============> The result was a Syntax error because str has been declared as parameter of function captialise before let reassign str.
+// =============>
 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
diff --git a/Sprint-3/1-key-errors/1.js b/Sprint-3/1-key-errors/1.js
index f2d56151f..6a42a9427 100644
--- a/Sprint-3/1-key-errors/1.js
+++ b/Sprint-3/1-key-errors/1.js
@@ -1,20 +1,17 @@
 // Predict and explain first...
 
 // Why will an error occur when this program runs?
-// =============> write your prediction here
+// =============> SyntaxError will occurs
 
 // Try playing computer with the example to work out what is going on
 
+// =============> decimalNumber first declared as parameter, it cannot be reassigned as const.
+// Also, console.log try to run decimalNumber as a variable while decimalNumber was assigned as a parameter.
+// Finally, correct the code to fix the problem
+// =============> write your new code here
 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(0.5));
diff --git a/Sprint-3/1-key-errors/2.js b/Sprint-3/1-key-errors/2.js
index aad57f7cf..9b96755f0 100644
--- a/Sprint-3/1-key-errors/2.js
+++ b/Sprint-3/1-key-errors/2.js
@@ -1,20 +1,17 @@
-
 // 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
-
-function square(3) {
-    return num * num;
-}
+// =============> I expect SyntaxError will result
 
-// =============> write the error message here
+// =============> SyntaxError: Unexpected number
 
-// =============> explain this error message here
+// =============> Numerical character "3" cannot be named as parameter of a function.
 
 // 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..2a0737b02 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
+// =============> Undefined at the end of sentence. console.log in local function will result the product. But console.log in global scope will not call function multiply.
 
-function multiply(a, b) {
-  console.log(a * b);
-}
-
-console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
+//function multiply(a, b) {
+//  console.log(a * b);
+//}
 
-// =============> write your explanation here
+//console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
 
+// =============> The function multiply does not really carry out the multiplication. It only logs the result of a*b. That's why calling multiply become 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..978eb0ef4 100644
--- a/Sprint-3/2-mandatory-debug/1.js
+++ b/Sprint-3/2-mandatory-debug/1.js
@@ -1,13 +1,18 @@
 // Predict and explain first...
-//  =============> write your prediction here
+//  =============> I predict a SyntaxError in original code
 
-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
+// =============> Expression a + b is not assigned to return. 
 // 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)}`);
\ No newline at end of file
diff --git a/Sprint-3/2-mandatory-debug/2.js b/Sprint-3/2-mandatory-debug/2.js
index 57d3f5dc3..705cd3563 100644
--- a/Sprint-3/2-mandatory-debug/2.js
+++ b/Sprint-3/2-mandatory-debug/2.js
@@ -1,11 +1,30 @@
 // Predict and explain first...
 
 // Predict the output of the following code:
-// =============> Write your prediction here
+// =============> Code returns last digit of 103 which is the value of num assigned in global scope.
 
+//const num = 103;
+
+//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)}`);
+
+// Now run the code and compare the output to your prediction
+// =============>
+// 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
+// =============> The function refers to the value of `num` assigned in global scope rather than getLastDigit, because 'num' was not a parameter in function name.
+// Finally, correct the code to fix the problem
+// =============>
 const num = 103;
 
-function getLastDigit() {
+function getLastDigit(num) {
   return num.toString().slice(-1);
 }
 
@@ -13,12 +32,5 @@ 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
-// Explain why the output is the way it is
-// =============> write your explanation here
-// Finally, correct the code to fix the problem
-// =============> write your new code here
-
 // 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..e410c6f10 100644
--- a/Sprint-3/3-mandatory-implement/1-bmi.js
+++ b/Sprint-3/3-mandatory-implement/1-bmi.js
@@ -16,4 +16,17 @@
 
 function calculateBMI(weight, height) {
   // return the BMI of someone based off their weight and height
+  return (weight / Math.pow(height, 2)).toFixed(1);
 }
+
+console.log(
+  `BMI base off weight in kg and height in metres is ${calculateBMI(70, 1.73)}`,
+);
+
+//draft pseudocode below
+//name of function calculateBMI
+//key word return
+//parameters : weight, height
+//formula weight / height x height
+//or weight / sqr height (by Method: Math.pow(parameter,power))
+//by Method .toFixed(1) to return BMI in string in one decimal place
diff --git a/Sprint-3/3-mandatory-implement/2-cases.js b/Sprint-3/3-mandatory-implement/2-cases.js
index 5b0ef77ad..bb1ada7b4 100644
--- a/Sprint-3/3-mandatory-implement/2-cases.js
+++ b/Sprint-3/3-mandatory-implement/2-cases.js
@@ -14,3 +14,14 @@
 // You will need to come up with an appropriate name for the function
 // Use the MDN string documentation to help you find a solution
 // This might help https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/toUpperCase
+
+//pseudocode draft below
+//Name of function upperSnakeCase
+//Parameter (userInputString) type: String
+//Method  .toUpperCase() .replaceAll("","_")
+//print by console.log (`${userInputString()`})
+
+function upperSnakeCase(userInputString) {
+  return userInputString.toUpperCase().replaceAll(" ", "_");
+}
+console.log(upperSnakeCase("hello world"));
diff --git a/Sprint-3/3-mandatory-implement/3-to-pounds.js b/Sprint-3/3-mandatory-implement/3-to-pounds.js
index 10754da73..a049229fa 100644
--- a/Sprint-3/3-mandatory-implement/3-to-pounds.js
+++ b/Sprint-3/3-mandatory-implement/3-to-pounds.js
@@ -4,3 +4,35 @@
 // 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 name toPound
+//identifier of prev code :
+// 1 penceString - user input ; Type: String, count length by .length
+// 2 penceStringWithoutTrailingP ; cut the tail p by .substring ()
+// 3 paddedPenceNumberString ; assign and prescribe target length of pence in three characters length by .padStart()
+// 4 pounds ; assign pounds from first character of paddedPenceNumberString, cut the last two character by .substring
+// 5 pence ; assign pence starting from last two character of paddedPenceNumberString
+// Parameter to name wholePenceStringWithP
+
+function toPound(wholePenceStringWithP) {
+  const penceStringWithoutTrailingP = wholePenceStringWithP.substring(
+    0,
+    wholePenceStringWithP.length - 1,
+  );
+
+  const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+  const pounds = paddedPenceNumberString.substring(
+    0,
+    paddedPenceNumberString.length - 2,
+  );
+
+  const pence = paddedPenceNumberString.substring(
+    paddedPenceNumberString.length - 2,
+  );
+
+  return `£${pounds}.${pence}`;
+}
+console.log(toPound("399p"));
+console.log(toPound("1399p"));
+console.log(toPound("99p"));
+console.log(toPound("9p"));
\ No newline at end of file
diff --git a/Sprint-3/4-mandatory-interpret/time-format.js b/Sprint-3/4-mandatory-interpret/time-format.js
index c0dd9c9a5..da5cf085c 100644
--- a/Sprint-3/4-mandatory-interpret/time-format.js
+++ b/Sprint-3/4-mandatory-interpret/time-format.js
@@ -15,24 +15,25 @@ 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
+// =============> Three 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
+// =============> 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 pad call takes `remainingSeconds` as its argument, and 61 % 60 =1 , so num 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
+// =============> 01. `numString` starts as "1", which has one character length. Since 1 < 1, the while lines run and pad "0", giving "01". Now this new `numString` has two characters length, so the while loop stops and returns "01".
diff --git a/Sprint-3/5-stretch-extend/format-time.js b/Sprint-3/5-stretch-extend/format-time.js
index 32a32e66b..eac4c14da 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 > 12) {
-    return `${hours - 12}:00 pm`;
+  const minutes = time.slice(-2);
+  if (hours > 22) {
+    return `${hours - 12}:${minutes} pm`;
+  } else if (hours > 12) {
+    return `0${hours - 12}:${minutes} pm`;
+  } else if (hours > 9) {
+    return `${hours}:${minutes} am`;
+  } else if (hours < 1) {
+    return `12:${minutes} am`;
   }
-  return `${time} am`;
+
+  return `0${hours}:${minutes} am`;
 }
 
-const currentOutput = formatAs12HourClock("08:00");
-const targetOutput = "08:00 am";
+const currentOutput = formatAs12HourClock("08:01");
+const targetOutput = "08:01 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("00:01");
+const targetOutput3 = "12:01 am";
+console.assert(
+  currentOutput3 === targetOutput3,
+  `current output: ${currentOutput3}, target output: ${targetOutput3}`,
+);
+
+const currentOutput4 = formatAs12HourClock("11:01");
+const targetOutput4 = "11:01 am";
+console.assert(
+  currentOutput4 === targetOutput4,
+  `current output: ${currentOutput4}, target output: ${targetOutput4}`,
+);
+
+console.log(formatAs12HourClock("08:01"));
+console.log(formatAs12HourClock("23:55"));
+console.log(formatAs12HourClock("00:01"));
+console.log(formatAs12HourClock("11:01"));
+console;
+
+//Two patches
+//First hour input > 24, current algo is hours - 12 , e.g. 25-12 and print 13:00pm , rather than 1:00am (+1)
+//to Define `hoursOfOneDay` = 24
+//2 min input
+//to Define