diff --git a/Sprint-2/1-key-exercises/1-count.js b/Sprint-2/1-key-exercises/1-count.js
index 117bcb2b6..70fa5c7c1 100644
--- a/Sprint-2/1-key-exercises/1-count.js
+++ b/Sprint-2/1-key-exercises/1-count.js
@@ -4,3 +4,6 @@ count = count + 1;
 
 // Line 1 is a variable declaration, creating the count variable with an initial value of 0
 // Describe what line 3 is doing, in particular focus on what = is doing
+
+//= mean assignment operator. Computer will calculate the result of "count + 1" and update the variable with the result.
+//In this question, variable "count" changed from 0 to 1.
diff --git a/Sprint-2/1-key-exercises/2-initials.js b/Sprint-2/1-key-exercises/2-initials.js
index 964c9563c..0af5287dd 100644
--- a/Sprint-2/1-key-exercises/2-initials.js
+++ b/Sprint-2/1-key-exercises/2-initials.js
@@ -5,6 +5,7 @@ const lastName = "Johnson";
 // Declare a variable called initials that stores the first character of each string.
 // This should produce the string "CKJ", but you must not write the characters C, K, or J in the code of your solution.
 
-const initials = ``;
+const initials = `${firstName.charAt(0)}${middleName.charAt(0)}${lastName.charAt(0)}`;
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn
+console.log(initials);
diff --git a/Sprint-2/1-key-exercises/3-paths.js b/Sprint-2/1-key-exercises/3-paths.js
index ab90ebb28..1aa19f329 100644
--- a/Sprint-2/1-key-exercises/3-paths.js
+++ b/Sprint-2/1-key-exercises/3-paths.js
@@ -11,13 +11,15 @@
 
 const filePath = "/Users/mitch/cyf/Module-JS1/week-1/interpret/file.txt";
 const lastSlashIndex = filePath.lastIndexOf("/");
-const base = filePath.slice(lastSlashIndex + 1);
+const base = filePath.slice(lastSlashIndex);
 console.log(`The base part of ${filePath} is ${base}`);
 
 // Create a variable to store the dir part of the filePath variable
 // Create a variable to store the ext part of the variable
 
-const dir = ;
-const ext = ;
+const dir = filePath.slice(0, lastSlashIndex);
+const ext = base.slice(base.lastIndexOf(".") + 1);
 
-// https://www.google.com/search?q=slice+mdn
\ No newline at end of file
+console.log(ext);
+
+// https://www.google.com/search?q=slice+mdn
diff --git a/Sprint-2/1-key-exercises/4-random.js b/Sprint-2/1-key-exercises/4-random.js
index 292f83aab..c66d73d8d 100644
--- a/Sprint-2/1-key-exercises/4-random.js
+++ b/Sprint-2/1-key-exercises/4-random.js
@@ -7,3 +7,10 @@ const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
 // Try breaking down the expression and using documentation to explain what it means
 // It will help to think about the order in which expressions are evaluated
 // Try logging the value of num and running the program several times to build an idea of what the program is doing
+
+console.log(num);
+
+//math.floor is round down the number returns to largest integer less than or equal to a given number.
+//math.random() could generate the number from 0 to <1 b random.
+//maximum refer to 100 and minimum refer to 1.
+//The calculation of num is different everytime because of math.random(). smallest value of num is 1. And largest is 100.
diff --git a/Sprint-2/2-mandatory-errors/0.js b/Sprint-2/2-mandatory-errors/0.js
index cf6c5039f..565030121 100644
--- a/Sprint-2/2-mandatory-errors/0.js
+++ b/Sprint-2/2-mandatory-errors/0.js
@@ -1,2 +1,4 @@
-This is just an instruction for the first activity - but it is just for human consumption
-We don't want the computer to run these 2 lines - how can we solve this problem?
\ No newline at end of file
+//This is just an instruction for the first activity - but it is just for human consumption
+//We don't want the computer to run these 2 lines - how can we solve this problem?
+
+//adding // before the lines.
diff --git a/Sprint-2/2-mandatory-errors/1.js b/Sprint-2/2-mandatory-errors/1.js
index 7a43cbea7..0a30f0492 100644
--- a/Sprint-2/2-mandatory-errors/1.js
+++ b/Sprint-2/2-mandatory-errors/1.js
@@ -1,4 +1,9 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+let age = 33;
 age = age + 1;
+
+console.log(age);
+
+//The error is "Assignment to constant variable." Constant value could not be alternated.
+//if line 3 const changed to let the code could be executed.
diff --git a/Sprint-2/2-mandatory-errors/2.js b/Sprint-2/2-mandatory-errors/2.js
index e09b89831..acebcee09 100644
--- a/Sprint-2/2-mandatory-errors/2.js
+++ b/Sprint-2/2-mandatory-errors/2.js
@@ -1,5 +1,8 @@
 // Currently trying to print the string "I was born in Bolton" but it isn't working...
 // what's the error ?
 
-console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);
+
+//Initiation should access before the declaration.
+//error message: Error: ReferenceError: Cannot access 'cityOfBirth' before initialization
diff --git a/Sprint-2/2-mandatory-errors/3.js b/Sprint-2/2-mandatory-errors/3.js
index ec101884d..7625740fa 100644
--- a/Sprint-2/2-mandatory-errors/3.js
+++ b/Sprint-2/2-mandatory-errors/3.js
@@ -1,5 +1,7 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+const last4Digits = cardNumber.toString().slice(-4);
+
+console.log(last4Digits);
 
 // The last4Digits variable should store the last 4 digits of cardNumber
 // However, the code isn't working
@@ -7,3 +9,8 @@ const last4Digits = cardNumber.slice(-4);
 // Then run the code and see what error it gives.
 // Consider: Why does it give this error? Is this what I predicted? If not, what's different?
 // Then try updating the expression last4Digits is assigned to, in order to get the correct value
+
+//slice is for text or array only. Need to change card number from number to text. use toString() to convert cardNumber
+//from integer to string.
+
+//error message: TypeError: cardNumber.slice is not a function
diff --git a/Sprint-2/2-mandatory-errors/4.js b/Sprint-2/2-mandatory-errors/4.js
index 5f86c730b..a9713c54f 100644
--- a/Sprint-2/2-mandatory-errors/4.js
+++ b/Sprint-2/2-mandatory-errors/4.js
@@ -1,2 +1,5 @@
-const 12HourClockTime = "8:53pm";
-const 24hourClockTime = "20:53";
+const twelveClockTime = "8:53pm";
+const twentyFourHourClockTime = "20:53";
+
+//integer and number could not start for the initiation.
+//SyntaxError: Invalid or unexpected token - print before modified the initiation.
diff --git a/Sprint-2/3-mandatory-interpret/1-percentage-change.js b/Sprint-2/3-mandatory-interpret/1-percentage-change.js
index e24ecb8e1..702572043 100644
--- a/Sprint-2/3-mandatory-interpret/1-percentage-change.js
+++ b/Sprint-2/3-mandatory-interpret/1-percentage-change.js
@@ -2,7 +2,7 @@ let carPrice = "10,000";
 let priceAfterOneYear = "8,543";
 
 carPrice = Number(carPrice.replaceAll(",", ""));
-priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
 
 const priceDifference = carPrice - priceAfterOneYear;
 const percentageChange = (priceDifference / carPrice) * 100;
@@ -12,11 +12,23 @@ console.log(`The percentage change is ${percentageChange}`);
 // Read the code and then answer the questions below
 
 // a) How many function calls are there in this file? Write down all the lines where a function call is made
+//A: 5
+//carPrice = Number(carPrice.replaceAll(",", ""));
+//priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+//console.log(`The percentage change is ${percentageChange}`);
 
 // b) Run the code and identify the line where the error is coming from - why is this error occurring? How can you fix this problem?
+//A: line 5. there should add , between "," and "" to divided 2 conditions.
 
 // c) Identify all the lines that are variable reassignment statements
+//A: carPrice = Number(carPrice.replaceAll(",", ""));
+//priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
 
 // d) Identify all the lines that are variable declarations
+//const priceDifference = carPrice - priceAfterOneYear;
+//const percentageChange = (priceDifference / carPrice) * 100;
+//let carPrice = "10,000";
+//let priceAfterOneYear = "8,543";
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+//A: replacing , with empty string. number() is convert text to number.
diff --git a/Sprint-2/3-mandatory-interpret/2-time-format.js b/Sprint-2/3-mandatory-interpret/2-time-format.js
index 47d239558..7e03bcbb4 100644
--- a/Sprint-2/3-mandatory-interpret/2-time-format.js
+++ b/Sprint-2/3-mandatory-interpret/2-time-format.js
@@ -12,14 +12,23 @@ console.log(result);
 // For the piece of code above, read the code and then answer the following questions
 
 // a) How many variable declarations are there in this program?
+// A: 6
 
 // b) How many function calls are there?
+//A: 1
 
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
+// % operate the remainder of 2 numbers divided. In this case, remainingSecond is the remainder of  8784 second (movieLength)
+// divided 60. And the remainingSecond is 24.
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+//A: totalMinutes get the result form movieLength (8784) minus remainingSecond (24). The result is 8760.
+//The totalMinutes is 8760 divide 60 = 146.
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+//A: Duration
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+// Only integer and positive value could work. If movieLength changed to negative value and decimal value, result could
+// not show in correct time format.
diff --git a/Sprint-2/3-mandatory-interpret/3-to-pounds.js b/Sprint-2/3-mandatory-interpret/3-to-pounds.js
index 60c9ace69..cf2e0a352 100644
--- a/Sprint-2/3-mandatory-interpret/3-to-pounds.js
+++ b/Sprint-2/3-mandatory-interpret/3-to-pounds.js
@@ -2,13 +2,13 @@ const penceString = "399p";
 
 const penceStringWithoutTrailingP = penceString.substring(
   0,
-  penceString.length - 1
+  penceString.length - 1,
 );
 
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
 const pounds = paddedPenceNumberString.substring(
   0,
-  paddedPenceNumberString.length - 2
+  paddedPenceNumberString.length - 2,
 );
 
 const pence = paddedPenceNumberString
@@ -25,3 +25,11 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 2. const penceStringWithoutTrailingP = "399": returning with shorten less index to erase p
+// 3. const paddedPenceNumberString = "399"; It pads the string with the given length with specific string.
+// In this case, penceStringWithoutTrailingP (399) is already with 3 digis, so no change.
+// 4. const pounds = "3", getting part of the string by subString and target to get the string without last 2 digis.
+// 5. const pence = "99", subString indexStart counted by length of paddedPenceNumberString - 2 that is 1. So the result of
+//subString is 99. padEnd result the string with given length from the end of String. "99" length is 2 and already match
+//with the function. no change.
+//6. console.log = £3.99. The number refer to pounds and pence.
diff --git a/Sprint-2/4-stretch-explore/chrome.md b/Sprint-2/4-stretch-explore/chrome.md
index 962580b82..f2ea5519c 100644
--- a/Sprint-2/4-stretch-explore/chrome.md
+++ b/Sprint-2/4-stretch-explore/chrome.md
@@ -8,8 +8,11 @@ Let's try an example.
 In the Chrome console, invoke the function `alert` with one argument, the string `"Hello world!"`;
 
 What effect does calling the `alert` function have?
+A: The dialogue box come out with an optional message.
 
 Now try invoking the function `prompt` with a string input of `"What is your name?"` - store the return value of your call to `prompt` in an variable called `myName`.
 
 What effect does calling the `prompt` function have?
 What is the return value of `prompt`?
+A: There have a dialogue box appear and able to submit information.
+After submit the information (Name). The information submitted to server.
diff --git a/Sprint-2/4-stretch-explore/objects.md b/Sprint-2/4-stretch-explore/objects.md
index 0216dee56..d0a82a098 100644
--- a/Sprint-2/4-stretch-explore/objects.md
+++ b/Sprint-2/4-stretch-explore/objects.md
@@ -5,12 +5,98 @@ In this activity, we'll explore some additional concepts that you'll encounter i
 Open the Chrome devtools Console, type in `console.log` and then hit enter
 
 What output do you get?
+A: ƒ log() { [native code] }
 
 Now enter just `console` in the Console, what output do you get back?
+A: console {debug: ƒ, error: ƒ, info: ƒ, log: ƒ, warn: ƒ, …}
 
 Try also entering `typeof console`
+A: 'object'
 
 Answer the following questions:
 
 What does `console` store?
+A： console {debug: ƒ, error: ƒ, info: ƒ, log: ƒ, warn: ƒ, …}
+assert
+:
+ƒ assert()
+clear
+:
+ƒ clear()
+context
+:
+ƒ context()
+count
+:
+ƒ count()
+countReset
+:
+ƒ countReset()
+createTask
+:
+ƒ createTask()
+debug
+:
+ƒ debug()
+dir
+:
+ƒ dir()
+dirxml
+:
+ƒ dirxml()
+error
+:
+ƒ error()
+group
+:
+ƒ group()
+groupCollapsed
+:
+ƒ groupCollapsed()
+groupEnd
+:
+ƒ groupEnd()
+info
+:
+ƒ info()
+log
+:
+ƒ log()
+memory
+:
+MemoryInfo {totalJSHeapSize: 12700000, usedJSHeapSize: 11200000, jsHeapSizeLimit: 3760000000}
+profile
+:
+ƒ profile()
+profileEnd
+:
+ƒ profileEnd()
+table
+:
+ƒ table()
+time
+:
+ƒ time()
+timeEnd
+:
+ƒ timeEnd()
+timeLog
+:
+ƒ timeLog()
+timeStamp
+:
+ƒ timeStamp()
+trace
+:
+ƒ trace()
+warn
+:
+ƒ warn()
+Symbol(Symbol.toStringTag)
+:
+"console"
+[[Prototype]]
+:
+Object
 What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+A：log and assert are the functions under object "console". '.' mean calling for function.
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..5fe106961 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)}`);
 
 // =============> 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..c2e9d1493 100644
--- a/Sprint-3/2-mandatory-debug/2.js
+++ b/Sprint-3/2-mandatory-debug/2.js
@@ -2,23 +2,44 @@
 
 // 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 get the last digit of 42, 105 and 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..480aeb70c 100644
--- a/Sprint-3/3-mandatory-implement/1-bmi.js
+++ b/Sprint-3/3-mandatory-implement/1-bmi.js
@@ -15,5 +15,10 @@
 // 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);
+  const result = Math.floor(rawBMI * 10) / 10;
+
+  return result;
 }
+
+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..7004f2401 100644
--- a/Sprint-3/3-mandatory-implement/2-cases.js
+++ b/Sprint-3/3-mandatory-implement/2-cases.js
@@ -14,3 +14,10 @@
 // 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.replace(" ", "_");
+}
+
+console.log(upperSnakeCase("hello there"));
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..93383d016 100644
--- a/Sprint-3/4-mandatory-interpret/time-format.js
+++ b/Sprint-3/4-mandatory-interpret/time-format.js
@@ -15,24 +15,26 @@ 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
+// =============> 4
 
 // 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
+// =============> 1
 
 // c) What is the return value of pad when it is called for the first time?
-// =============> write your answer here
+// =============> "01"
 
 // 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
+// =============> 0. The last calling of pad is pad(totalHours). the calculation is 1 (totalMinutues) - 1 (remainingMinutes. The result is 0.)
 
 // 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
+// =============> 1. pad(remainingSeconds is the last calling foe pad.