diff --git a/Sprint-1/1-key-exercises/1-count.js b/Sprint-1/1-key-exercises/1-count.js
index 117bcb2b6e..f79c6f1216 100644
--- a/Sprint-1/1-key-exercises/1-count.js
+++ b/Sprint-1/1-key-exercises/1-count.js
@@ -4,3 +4,10 @@ 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 updating the value of the count variable. The = operator is an 
+// assignment operator, which assigns the value on the right side 
+// (count + 1) to the variable on the left side (count). In this case, 
+// it takes the current value of count (which is 0), adds 1 to it, and then 
+// assigns the result (1) back to count. So after line 3 executes, count will 
+// have a new value of 1.
\ No newline at end of file
diff --git a/Sprint-1/1-key-exercises/2-initials.js b/Sprint-1/1-key-exercises/2-initials.js
index 47561f6175..edf69a79ff 100644
--- a/Sprint-1/1-key-exercises/2-initials.js
+++ b/Sprint-1/1-key-exercises/2-initials.js
@@ -5,7 +5,9 @@ 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.charAt(0) + middleName.charAt(0) + lastName.charAt(0);
+
+console.log(initials); // Output: "CKJ"
 
 // 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 ab90ebb28e..aef461d986 100644
--- a/Sprint-1/1-key-exercises/3-paths.js
+++ b/Sprint-1/1-key-exercises/3-paths.js
@@ -17,7 +17,9 @@ 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);
 
+console.log(`The dir part of ${filePath} is ${dir}`);
+console.log(`The ext part of ${filePath} is ${ext}`);
 // https://www.google.com/search?q=slice+mdn
\ No newline at end of file
diff --git a/Sprint-1/1-key-exercises/4-random.js b/Sprint-1/1-key-exercises/4-random.js
index 292f83aabb..5e3f25f50b 100644
--- a/Sprint-1/1-key-exercises/4-random.js
+++ b/Sprint-1/1-key-exercises/4-random.js
@@ -7,3 +7,14 @@ 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()= rounds a number down to the nearest integer
+// Math.random() = generates a random float number between 0 and 1 (not including 1)
+// Math.random() * 100 = generates a random float number between 0 and 99.999...
+// (maximum - minimum + 1) -> scales the range of random numbers to be between the minimum and maximum values (including the maximum value)
+// + minimum -> shifts the range of random numbers to start from the minimum value instead of 0
+// So, the expression generates a random integer between the minimum and maximum values (inclusive)
+// num = a random integer between 1 and 100 (including 100)
+
diff --git a/Sprint-1/2-mandatory-errors/0.js b/Sprint-1/2-mandatory-errors/0.js
index cf6c5039f7..6a7a7f6908 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?
\ No newline at end of file
diff --git a/Sprint-1/2-mandatory-errors/1.js b/Sprint-1/2-mandatory-errors/1.js
index 7a43cbea76..031839b47d 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 e09b89831d..c506b10028 100644
--- a/Sprint-1/2-mandatory-errors/2.js
+++ b/Sprint-1/2-mandatory-errors/2.js
@@ -1,5 +1,7 @@
 // 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}`);
+
+// cityOfBirth has to be declared as a variable before we can use it in the console.log statement.
\ No newline at end of file
diff --git a/Sprint-1/2-mandatory-errors/3.js b/Sprint-1/2-mandatory-errors/3.js
index ec101884db..ffccdbcb62 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 = cardNumber.toString().slice(-4);
 
 // The last4Digits variable should store the last 4 digits of cardNumber
 // However, the code isn't working
@@ -7,3 +7,17 @@ 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: I think the code won't work because cardNumber is a number and the
+//  slice method is for strings. So, it will give an error that slice is not a function.
+
+// Error: TypeError: cardNumber.slice is not a function
+// It was what I predicted. This is because it occurs because cardNumber is a number,
+// and numbers do not have the slice method. To fix this, we can convert cardNumber 
+// to a string before using the slice method.
+
+// Fix: I converted cardNumber to a string using the toString() method, and then
+// I used the slice method to get the last 4 digits. The updated code is above.
+
+console.log(last4Digits);
+
diff --git a/Sprint-1/2-mandatory-errors/4.js b/Sprint-1/2-mandatory-errors/4.js
index 5f86c730bc..1302d31588 100644
--- a/Sprint-1/2-mandatory-errors/4.js
+++ b/Sprint-1/2-mandatory-errors/4.js
@@ -1,2 +1,7 @@
-const 12HourClockTime = "8:53pm";
-const 24hourClockTime = "20:53";
+const twelveHourClockTime = "8:53pm";
+const twentyFourHourClockTime = "20:53";
+
+// Found out that variable names cannot start with a number in JavaScript. 
+// To fix this, we can rename the variables to start with a letter or an 
+// underscore. 
+// In this instance I spelled out the numbers as words.
\ No newline at end of file
diff --git a/Sprint-1/3-mandatory-interpret/1-percentage-change.js b/Sprint-1/3-mandatory-interpret/1-percentage-change.js
index e24ecb8e18..b48457a644 100644
--- a/Sprint-1/3-mandatory-interpret/1-percentage-change.js
+++ b/Sprint-1/3-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
+// Line 4: replaceAll(",", "") and Number() 
+// Line 5: replaceAll(",", "") and Number() 
+// Line 10: 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?
+// Line 5 has a SyntaxError - there is a missing comma between "," and "" in replaceAll(",""  should be replaceAll(",", "")
 
 // c) Identify all the lines that are variable reassignment statements
+// Line 4: carPrice = ...
+// Line 5: priceAfterOneYear = ...
 
 // d) Identify all the lines that are variable declarations
+// Line 1: let carPrice = "10,000"
+// Line 2: let priceAfterOneYear = "8,543"
+// Line 7: const priceDifference = ...
+// Line 8: const percentageChange = ..
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+// replaceAll(",", "") removes all commas from the string e.g. "10,000" becomes "10000"
+// Number() then converts that string into an actual number so we can do maths on it
\ No newline at end of file
diff --git a/Sprint-1/3-mandatory-interpret/2-time-format.js b/Sprint-1/3-mandatory-interpret/2-time-format.js
index 47d2395587..61cf6b4ad5 100644
--- a/Sprint-1/3-mandatory-interpret/2-time-format.js
+++ b/Sprint-1/3-mandatory-interpret/2-time-format.js
@@ -12,14 +12,24 @@ 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?
+// 6 -> movieLength, remainingSeconds, totalMinutes, remainingMinutes, totalHours, result
 
 // b) How many function calls are there?
+// -> console.log() on the last line
 
 // c) Using documentation, explain what the expression movieLength % 60 represents
 // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
+// % is the modulo (remainder) operator. movieLength % 60 gives the leftover seconds
+// after dividing by 60. e.g. 8784 / 60 = 146 remainder 24, so remainingSeconds = 24
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+// movieLength - remainingSeconds gives the total number of seconds that can be divided into whole minutes.
+// Dividing this by 60 gives the total number of whole minutes in the movie. e.g. 8784 - 24 = 8760, 8760 / 60 = 146
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+// result represents the movie length formatted as hours:minutes:seconds e.g. "2:26:24"
+// A better name could be formattedMovieLength or totalFormattedMovieLength
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+// It works for any positive whole number of seconds.
+// It won't work correctly for negative values or decimals as % behaves unexpectedly with those.
\ No newline at end of file
diff --git a/Sprint-1/3-mandatory-interpret/3-to-pounds.js b/Sprint-1/3-mandatory-interpret/3-to-pounds.js
index 60c9ace69a..5f042fb59f 100644
--- a/Sprint-1/3-mandatory-interpret/3-to-pounds.js
+++ b/Sprint-1/3-mandatory-interpret/3-to-pounds.js
@@ -25,3 +25,8 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 2. penceString.substring(0, penceString.length - 1): removes the trailing "p" by taking all characters except the last one -> "399"
+// 3. paddedPenceNumberString = "399".padStart(3, "0"): ensures the string is at least 3 characters long, padding with "0" on the left if needed. "399" stays "399" but "5p" would become "005"
+// 4. pounds = paddedPenceNumberString.substring(0, length - 2): takes everything except the last 2 digits, giving the pounds part -> "3"
+// 5. pence = paddedPenceNumberString.substring(length - 2).padEnd(2, "0"): takes the last 2 digits for the pence -> "99". padEnd ensures it stays 2 digits e.g. "5" would become "50"
+// 6. console.log prints the final result combining pounds and pence -> £3.99
\ No newline at end of file