← IGCSE Computer Science Paper 1

Giving the answer in the unit asked

Finish a storage calculation by converting the result into the unit the question asks for, then write that unit with your answer, for example 2 MiB.

Part of: IGCSE Computer Science 0478 — 1.3 Data Storage and Compression — Module 15

Understanding Giving the answer in the unit asked in IGCSE Computer Science Paper 1

What it does: The full calculation is done first in bits. The conversion to KiB is the last step. Sizes in different units cannot be compared directly. Converting both to KiB shows 2 MiB is larger. The question names the unit, so the final answer must be in that unit. 8 388 608 ÷ 1024 ÷ 1024 = 8 MiB. Calculate the size in bits or bytes first, then convert the final result to the unit asked. This keeps the working simple and avoids mistakes. Always write the unit with the answer. A bare number does not say what size it is. 3 145 728 ÷ 1024 = 3072 KiB, then ÷ 1024 again = 3 MiB. 3072 is the size in KiB, so you stopped one step early.

Common mistakes: To change bits into bytes you divide by 8, not multiply. It should be bytes = bits / 8, so the later conversion to KiB gives 1 KiB. Going from bytes to a larger unit (MiB) means dividing by 1024 for each step up the ladder. It should be MiB = bytes / 1024 / 1024, which gives 4 MiB.

Class: _____________________  ·  Name: _____________________  ·  Date: _________

Free printable worksheet with full answer key — or add this module to a class and your students practise it interactively.

🖨 Print worksheet + answer key Add Giving the answer in the unit asked to a class →

This module's key terms are also in a printable crossword (Modules 69–84) and word search (Modules 59–84).

Take this worksheet further — free with Cloodit

Each concept is reinforced from every angle — learned, then applied, then tested.

Learning
Duo
A question asks for the file size in MiB. You have calculated 8 388 608 bytes. What is the next step?
Divide by 1024 twice to convert to MiBWrite 8 388 608 as the answer, because bytes are fine
Matches
The question asks for MiB. Answer: 4096 KiB
↓
The answer is left in KiB, not in the MiB the question asked for. It should be converted: 4096 / 1024 = 4 MiB.
Applying
Meanings
Term
unit asked
Meaning
Finish a storage calculation by converting the result into the unit the question asks for, then write that unit with your answer, for example 2 MiB.
Practice
size_bits ← 1024 * 768 * 8
Testing
Gaps
sizeKiB ← sizeBytes /
Check Answer
Spots
1bits = 8192
2bytes = bits * 8

Cloodit turns curriculum-aligned coding content into journeys students work through one biome at a time.

The 'Firefly' badge — Night Coder, one of Cloodit's 106 collectible badges
Students earn collectable badges

Over 100 of them, across seven natural biomes.

Study Buddy
Students build a real study resource

Turns their work into revision material ready for Flash Cards and Exam study.

Diamond Dash — one of Cloodit's live, competitive Sprint games
Students lock in with Sprints

Live, competitive practice for the start of the lesson or a teacher-led lesson finisher.

A Cloodit certificate of achievement, ready to personalise and print
Custom printable certificates

Honour your top performers, or encourage a student who's trying hard — ready to print in seconds.

Add to class →

Quick Questions

1. A question asks for the file size in MiB. You have calculated 8 388 608 bytes. What is the next step?
A. Divide by 1024 twice to convert to MiB ✓
B. Write 8 388 608 as the answer, because bytes are fine
The question names the unit, so the final answer must be in that unit. 8 388 608 ÷ 1024 ÷ 1024 = 8 MiB.
2. When should you convert the result to the unit the question asks for?
A. After finishing the calculation ✓
B. Before starting, by converting every value first
Calculate the size in bits or bytes first, then convert the final result to the unit asked. This keeps the working simple and avoids mistakes.
3. Which final answer is complete for a question that asks for the size in KiB?
A. 64
B. 64 KiB ✓
Always write the unit with the answer. A bare number does not say what size it is.
4. An image file is 3 145 728 bytes. The question asks for the size in MiB. What is the correct answer?
A. 3 MiB ✓
B. 3072 MiB
3 145 728 ÷ 1024 = 3072 KiB, then ÷ 1024 again = 3 MiB. 3072 is the size in KiB, so you stopped one step early.
5. A sound file is 24 000 bits. The question asks for the size in bytes. Which is correct?
A. 192 000 bytes
B. 3000 bytes ✓
To go from bits to bytes, divide by 8. 24 000 ÷ 8 = 3000 bytes. Multiplying by 8 goes the wrong way.

Match the Pairs

bits ÷ 8 ÷ 1024 = KiB → Convert a size in bits to kibibytes by dividing by 8 and then by 1024
Answer: 3 MiB → The answer is written with the unit that the question asked for
Work out the file size first, then convert it to the unit asked → size_bits = 1000 * 8 * 16 size_KiB = size_bits / 8 / 1024
To compare two file sizes fairly, convert both to the same unit → 2 MiB = 2048 KiB, so 2048 KiB > 1500 KiB
The question asks for MiB. Answer: 4096 KiB → The answer is left in KiB, not in the MiB the question asked for. It should be converted: 4096 / 1024 = 4 MiB.
Answer: 12 → The unit is missing. The answer should be written with the unit, such as 12 KiB.

Key Term

unit asked
Finish a storage calculation by converting the result into the unit the question asks for, then write that unit with your answer, for example 2 MiB.

Fill in the Blanks

1. sizeKiB ← sizeBytes / 1024
Hint: Type the number of bytes in one kibibyte, used to convert after the calculation is finished.
2. sizeMiB ← sizeKiB / 1024 OUTPUT sizeMiB
Hint: Type the variable that holds the final result in the unit the question asked for.
3. sizeGiB ← sizeMiB / 1024 OUTPUT sizeGiB & " GiB"
Hint: Type the unit to write after the number, matching the unit in the variable name.
4. sizeBytes ← pixels * depth / 8 sizeKiB ← sizeBytes / 1024
Hint: Type the operator that converts a result in bytes into a larger unit.
5. sizeAKiB ← sizeAMiB * 1024 OUTPUT sizeAKiB > sizeBKiB
Hint: Type the operator that converts a larger unit into a smaller one so both sizes can be compared in one unit.

Spot the Error

Question 1
A bits = 8192
B bytes = bits * 8
C KiB = bytes / 1024
D OUTPUT KiB & " KiB"
Line B — To change bits into bytes you divide by 8, not multiply. It should be bytes = bits / 8, so the later conversion to KiB gives 1 KiB.
Question 2
A bytes = 4 * 1024 * 1024
B MiB = bytes * 1024 * 1024
C OUTPUT MiB & " MiB"
Line B — Going from bytes to a larger unit (MiB) means dividing by 1024 for each step up the ladder. It should be MiB = bytes / 1024 / 1024, which gives 4 MiB.
Question 3
A asked = "KiB"
B size = bytes / 1048576
C OUTPUT size & " " & asked
Line B — The question asks for KiB, so bytes are divided by 1024 once. Dividing by 1048576 gives MiB, the wrong unit. It should be size = bytes / 1024.
Question 4
A fileA = 2048 // KiB
B fileB = 3 // MiB
C fileB = fileB / 1024 // KiB
D OUTPUT "B is larger"
Line C — Converting MiB to the smaller unit KiB means multiplying by 1024, not dividing. It should be fileB = fileB * 1024, giving 3072 KiB, so B is larger than 2048 KiB.
Question 5
A a = 1500 // bytes
B b = 2 // KiB
C bB = b * 1024 // bytes
D IF b > a THEN
E OUTPUT "B is bigger"
F ENDIF
Line D — b is in KiB but a is in bytes, so they cannot be compared directly. Compare the converted value: IF bB > a THEN (2048 bytes against 1500 bytes).

Student with a class code? Join your class →