diff --git a/Sprint-1/1-key-exercises/1-count.js b/Sprint-1/1-key-exercises/1-count.js
index 117bcb2b6..bad37e4b2 100644
--- a/Sprint-1/1-key-exercises/1-count.js
+++ b/Sprint-1/1-key-exercises/1-count.js
@@ -4,3 +4,5 @@ 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
+// Line 3 is an increment operation. The = operator is the assignment operator:
+// it evaluates the expression on the right (count + 1), then assigns the result back to count.
diff --git a/Sprint-1/1-key-exercises/2-initials.js b/Sprint-1/1-key-exercises/2-initials.js
index 47561f617..9ca17e49d 100644
--- a/Sprint-1/1-key-exercises/2-initials.js
+++ b/Sprint-1/1-key-exercises/2-initials.js
@@ -5,7 +5,5 @@ let 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.
 
-let initials = ``;
-
+let initials = firstName[0] + middleName[0] + lastName[0];
 // https://www.google.com/search?q=get+first+character+of+string+mdn
-
diff --git a/Sprint-1/1-key-exercises/3-paths.js b/Sprint-1/1-key-exercises/3-paths.js
index ab90ebb28..c388aece5 100644
--- a/Sprint-1/1-key-exercises/3-paths.js
+++ b/Sprint-1/1-key-exercises/3-paths.js
@@ -17,7 +17,6 @@ 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 = ;
-
-// https://www.google.com/search?q=slice+mdn
\ No newline at end of file
+const dir = filePath.slice(0, lastSlashIndex);
+const ext = filePath.slice(filePath.lastIndexOf("."));
+// https://www.google.com/search?q=slice+mdn
diff --git a/Sprint-1/1-key-exercises/4-random.js b/Sprint-1/1-key-exercises/4-random.js
index 292f83aab..5d5dca22f 100644
--- a/Sprint-1/1-key-exercises/4-random.js
+++ b/Sprint-1/1-key-exercises/4-random.js
@@ -7,3 +7,13 @@ 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);
+
+// num represents a random integer in the range [1, 100].
+// Breakdown:
+// 1. Math.random() returns a decimal number in the range [0, 1).
+// 2. (maximum - minimum + 1) calculates the size of the range, which is 100.
+// 3. Math.random() * 100 gives a decimal in the range [0, 100).
+// 4. Math.floor() rounds down to the nearest integer, giving a value in the range [0, 99].
+// 5. Adding minimum (1) shifts the range to [1, 100].
diff --git a/Sprint-1/2-mandatory-errors/0.js b/Sprint-1/2-mandatory-errors/0.js
index cf6c5039f..044add7ac 100644
--- a/Sprint-1/2-mandatory-errors/0.js
+++ b/Sprint-1/2-mandatory-errors/0.js
@@ -1,2 +1,2 @@
-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?
diff --git a/Sprint-1/2-mandatory-errors/1.js b/Sprint-1/2-mandatory-errors/1.js
index 7a43cbea7..031839b47 100644
--- a/Sprint-1/2-mandatory-errors/1.js
+++ b/Sprint-1/2-mandatory-errors/1.js
@@ -1,4 +1,4 @@
 // trying to create an age variable and then reassign the value by 1
 
-const age = 33;
+let age = 33;
 age = age + 1;
diff --git a/Sprint-1/2-mandatory-errors/2.js b/Sprint-1/2-mandatory-errors/2.js
index e09b89831..2865eb8a4 100644
--- a/Sprint-1/2-mandatory-errors/2.js
+++ b/Sprint-1/2-mandatory-errors/2.js
@@ -1,5 +1,5 @@
 // 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}`);
diff --git a/Sprint-1/2-mandatory-errors/3.js b/Sprint-1/2-mandatory-errors/3.js
index ec101884d..4616e75d9 100644
--- a/Sprint-1/2-mandatory-errors/3.js
+++ b/Sprint-1/2-mandatory-errors/3.js
@@ -1,5 +1,5 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+const last4Digits = String(cardNumber).slice(-4);
 
 // The last4Digits variable should store the last 4 digits of cardNumber
 // However, the code isn't working
@@ -7,3 +7,8 @@ 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
+
+// Prediction: The original code will throw a TypeError because .slice() is a string method,
+// and cardNumber is a number, not a string. Numbers do not have a .slice() method.
+// Fix: We use String(cardNumber) to convert the number to a string first,
+// then call .slice(-4) to extract the last 4 characters: "4213".
diff --git a/Sprint-1/2-mandatory-errors/4.js b/Sprint-1/2-mandatory-errors/4.js
index 21dad8c5d..e48324f14 100644
--- a/Sprint-1/2-mandatory-errors/4.js
+++ b/Sprint-1/2-mandatory-errors/4.js
@@ -1,2 +1,2 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
\ No newline at end of file
+const twelveHourClockTime = "20:53";
+const twentyFourHourClockTime = "08:53";
diff --git a/Sprint-1/3-mandatory-interpret/1-percentage-change.js b/Sprint-1/3-mandatory-interpret/1-percentage-change.js
index e24ecb8e1..1aac538a9 100644
--- a/Sprint-1/3-mandatory-interpret/1-percentage-change.js
+++ b/Sprint-1/3-mandatory-interpret/1-percentage-change.js
@@ -2,8 +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 +11,24 @@ 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
+// There are 5 function calls:
+// Line 4: replaceAll(",", "") and Number()
+// Line 5: replaceAll(",", "") and Number()
+// Line 9: console.log()
 
 // 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?
+// The original code on line 5 was: priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+// This causes a SyntaxError because there is a missing comma between the two arguments of replaceAll().
+// The original code had replaceAll("," "") but it should be replaceAll(",", "").
+// The comma between "," and "" is needed to separate the two arguments of the function.
+// The fix is simply adding the missing comma: replaceAll(",", "")
 
 // c) Identify all the lines that are variable reassignment statements
+// Lines 4 and 5 are variable reassignment statements (carPrice and priceAfterOneYear are reassigned using let).
 
 // d) Identify all the lines that are variable declarations
+// Lines 1, 2, 6, 7 are variable declarations (using let or const).
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+// It removes all commas from the string "10,000" to get "10000",
+// then converts that string into the number 10000 using Number().
diff --git a/Sprint-1/3-mandatory-interpret/2-time-format.js b/Sprint-1/3-mandatory-interpret/2-time-format.js
index 47d239558..62440f62a 100644
--- a/Sprint-1/3-mandatory-interpret/2-time-format.js
+++ b/Sprint-1/3-mandatory-interpret/2-time-format.js
@@ -12,14 +12,19 @@ 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?
+// There are 6 variable declarations (movieLength, remainingSeconds, totalMinutes, remainingMinutes, totalHours, result).
 
 // b) How many function calls are there?
+// There is 1 function call: console.log().
 
 // c) Using documentation, explain what the expression movieLength % 60 represents
-// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
+// The % operator gives the remainder. It calculates the remaining seconds that don't make up a full minute.
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// It subtracts the extra seconds to get a clean number, then divides by 60 to find the total whole minutes.
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+// It represents the formatted duration of the movie (Hours:Minutes:Seconds). A better name would be 'formattedDuration'.
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+// It works for positive integers, but it doesn't add a leading zero to single digits (e.g., it prints 2:5:9 instead of 02:05:09).
diff --git a/Sprint-1/3-mandatory-interpret/3-to-pounds.js b/Sprint-1/3-mandatory-interpret/3-to-pounds.js
index 60c9ace69..c59b9f92e 100644
--- a/Sprint-1/3-mandatory-interpret/3-to-pounds.js
+++ b/Sprint-1/3-mandatory-interpret/3-to-pounds.js
@@ -17,11 +17,32 @@ const pence = paddedPenceNumberString
 
 console.log(`£${pounds}.${pence}`);
 
-// This program takes a string representing a price in pence
-// The program then builds up a string representing the price in pounds
+// Step-by-step breakdown:
 
-// You need to do a step-by-step breakdown of each line in this program
-// Try and describe the purpose / rationale behind each step
+// 1. const penceString = "399p";
+// Declares a string variable with the value "399p".
 
-// To begin, we can start with
-// 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 2. const penceStringWithoutTrailingP = penceString.substring(0, penceString.length - 1);
+// Removes the trailing 'p' character, resulting in "399".
+
+// 3. const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+// Pads the string to at least 3 characters with leading zeros. "399" stays "399", but "5" would become "005".
+
+// 4. const pounds = paddedPenceNumberString.substring(0, paddedPenceNumberString.length - 2);
+// Extracts all characters except the last two to get the pounds part. "399" becomes "3".
+
+// 5. const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0");
+// Extracts the last two characters for the pence part and pads with trailing "0" if needed.
+
+// 6. console.log(`£${pounds}.${pence}`);
+// Outputs the formatted currency: £3.99
+
+// Question: Do we really need .padEnd(2, "0") in this script?
+// No, we do not actually need .padEnd(2, "0") in this script.
+// Because .padStart(3, "0") already guarantees the string has at least 3 characters,
+// .substring(length - 2) will always extract exactly 2 characters for the pence part.
+// For example:
+//   "5p"   -> "5" -> padStart -> "005" -> pence = "05" (already 2 chars, padEnd does nothing)
+//   "50p"  -> "50" -> padStart -> "050" -> pence = "50" (already 2 chars, padEnd does nothing)
+//   "399p" -> "399" -> padStart -> "399" -> pence = "99" (already 2 chars, padEnd does nothing)
+// So .padEnd(2, "0") is redundant here because padStart already ensures enough characters.