SLIDE 1
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Edexcel 1CP2 · Topic 2 · 2.1b
Hexadecimal
Number System
Base 16 · Hex to Binary · Hex to Denary · Uses of Hex
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Edexcel GCSE Computer Science 1CP2
What is Hexadecimal?
Base 16 — 16 Possible Digits
Denary
Binary
Hex
Denary
Binary
Hex
0
0000
0
8
1000
8
1
0001
1
9
1001
9
10
1010
A
11
1011
B
12
1100
C
13
1101
D
14
1110
E
15
1111
F
Each hex digit represents exactly
4 bits
— making hex a compact way to represent binary
Converting Hex ↔ Binary
Group Binary into Nibbles (4 bits)
Binary → Hex:
1010 1111 = A F =
AF
Hex → Binary:
3B = 0011 1011 =
00111011
Split 8-bit binary into two groups of 4 bits; convert each group to its hex equivalent
Easy shortcut: hex ↔ binary conversions require no complex arithmetic
Why Use Hexadecimal?
Real-World Uses
Memory addresses
— RAM addresses in hex are shorter and easier to read than long binary strings
Colour codes
— HTML/CSS colours: #FF5733 = red 255, green 87, blue 51
Error codes
— Windows Blue Screen of Death error codes displayed in hex
MAC addresses
— network hardware identifier: e.g. A4:C3:F0:85:AC:2D
Exam Practice
Have a go at this question
Edexcel-style question
Convert the hexadecimal number B4 into binary. Show your working.
2 marks
B = 1011 [1 mark]
4 = 0100 [1 mark]
B4 =
10110100
Key Takeaways
What to Remember
Hex is base 16: digits 0–9 then A(10), B(11), C(12), D(13), E(14), F(15)
Each hex digit = 4 binary bits (a nibble)
Hex used for: memory addresses, colour codes, error codes, MAC addresses
Hex ↔ Binary: group 4 bits per digit — no complex calculation needed