Edexcel 1CP2 · GCSE Computer Science · ~13 min read · 🔒 Pro
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What is Hexadecimal?
Hexadecimal (hex) is a base-16 number system. It uses 16 digits: 0–9 and A–F, where A=10, B=11, C=12, D=13, E=14, F=15. Each hex digit represents exactly 4 binary bits (a nibble), making hex a compact and human-readable way to express binary data.
Hex Digits Table
Denary
Binary
Hex
Denary
Binary
Hex
0
0000
0
8
1000
8
1
0001
1
9
1001
9
2
0010
2
10
1010
A
3
0011
3
11
1011
B
4
0100
4
12
1100
C
5
0101
5
13
1101
D
6
0110
6
14
1110
E
7
0111
7
15
1111
F
Binary to Hex
Split the binary number into groups of 4 bits (from the right), then convert each group to its hex digit.
Example: Convert 10110111 to hex
Split: 1011 | 0111 → B | 7 → B7
Hex to Binary
Replace each hex digit with its 4-bit binary equivalent.
Example: Convert 3F to binary
3 = 0011, F = 1111 → 00111111
Hex to Denary
Use column values: 16⁰=1, 16¹=16, 16²=256...
Example: Convert A9 to denary
A=10, 9=9 → (10×16) + (9×1) = 160 + 9 = 169
Why Use Hexadecimal?
Much shorter than binary — 8 bits = 2 hex digits
Easier to read and remember for humans
Used in: MAC addresses, HTML colour codes, memory addresses, error codes, assembly language
HTML colours: #FF6600 (orange) — FF=red, 66=green, 00=blue
MAC address: 00:1A:2B:3C:4D:5E
Exam tip: Always learn the hex digits A–F by heart: A=10, B=11, C=12, D=13, E=14, F=15. For binary↔hex, remember each hex digit = exactly 4 bits. For hex↔denary, use the column value method (× 16 for two-digit hex). State reasons for using hex: shorter than binary, easier to read, used in MAC addresses and HTML colours.
⚠️ Common Mistakes
Forgetting that hex is base 16 — it has 16 digits (0–9, A–F), not 10
Not grouping binary in groups of 4 from the RIGHT — e.g. 101 should be padded to 0101
Confusing hex F with denary 10 — F=15, not 10 (that's A)
In hex to denary: forgetting to multiply the left digit by 16
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Worksheet — 2.1b Hexadecimal
8 Edexcel-style questions · instantly marked
Q1State the hexadecimal equivalents of denary values 10, 12, and 15.[3]
✅ Mark scheme
10=A [1] / 12=C [1] / 15=F [1]
Q2Convert binary 11001101 to hexadecimal. Show your working.[3]
Q4Convert hexadecimal B3 to denary. Show your working.[3]
✅ Mark scheme
B=11, 3=3 [1] / (11×16)+(3×1)=176+3 [1] / 179 [1]
Q5Give two reasons why hexadecimal is used instead of binary when writing data.[2]
✅ Mark scheme
Hex is shorter/more compact than binary [1]; easier for humans to read and remember / less chance of error [1].
Q6The HTML colour code #FF0000 is used to represent a colour. Explain what the FF represents and state the colour produced.[2]
✅ Mark scheme
FF = maximum red (255 in denary) [1]; the colour is pure red [1].
Q7Convert binary 10100011 to hexadecimal.[2]
✅ Mark scheme
1010=A, 0011=3 → A3 [2] (1 mark for correct method, 1 for correct answer)
Q8State one real-world use of hexadecimal and explain why hex is appropriate for that use.[2]
✅ Mark scheme
E.g. MAC addresses [1] — they represent 48-bit values which would be very long in binary; hex compresses them into 12 digits that are easier to read [1]. Other answers: HTML colour codes, memory addresses, error codes.
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Mini Test — Hexadecimal
Timed exam-style test.
⏱10:00
Section A — Multiple Choice [5 marks]
Q1Hexadecimal is base:[1]
Q2Binary 1111 0000 in hex is:[1]
Q3Hex 1A in denary is:[1]
Q4Each hex digit represents how many binary bits?[1]
Q5Hex D in denary is:[1]
Section B — Short Answer
Q6Convert binary 10101010 to hexadecimal. Show working.[3]
Mark schemeSplit: 1010 | 1010 [1] / 1010=A, 1010=A [1] / AA [1]
Q7Give two reasons why hexadecimal is used instead of binary.[2]
Mark schemeShorter/more compact than binary [1]; easier to read/remember for humans / less likely to make errors [1].