← IGCSE Computer Science Paper 1

Hexadecimal digits 0 to 9 and A to F

The 16 hex digits: 0-9, then A=10, B=11, C=12, D=13, E=14, F=15. Each digit stands for one 4-bit value, and F (15) is the largest single hex digit.

Part of: IGCSE Computer Science 0478 — 1.1 Number Systems — Module 13, IGCSE Computer Science 0478 — 3.4 Network Hardware — Module 4

Understanding Hexadecimal digits 0 to 9 and A to F in IGCSE Computer Science Paper 1

What it does: This string lists all 16 hex digits in order: ten numbers then six letters. The letters follow on from 9 in order: A=10, B=11, C=12, D=13, so D is worth 13. A=10, so B=11. The letters count up from A=10 to F=15. Hex goes past 9 using letters, and F=15 is the largest single digit. Hex only uses 0-9 and A-F. G is not a hex digit. Hex is base 16: the digits 0-9 plus the six letters A-F make 16 digits. Each hex digit matches one 4-bit value, from 0000 to 1111. A=10, B=11, C=12, D=13, E=14, F=15.

Common mistakes: In hexadecimal C stands for 12, not 13. D is 13. The letters go A=10, B=11, C=12, D=13, E=14, F=15. F is worth 15. Hex has 16 digits but they run from 0 to 15, so no single hex digit is worth 16.

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

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This module's key terms are also in a printable crossword (Modules 3–17) and word search (Modules 3–27).

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Learning
Duo
What denary value does the hex digit B represent?
1211
Matches
A = 11
↓
A is worth 10, not 11. B is 11. The letters start at 10 and go up in order to F=15.
Applying
Meanings
Term
0123456789ABCDEF
Meaning
The 16 hex digits: 0-9, then A=10, B=11, C=12, D=13, E=14, F=15. Each digit stands for one 4-bit value, and F (15) is the largest single hex digit.
Practice
Digits: 0123456789ABCDEF
Testing
Gaps
Hex digit A = in denary
Check Answer
Spots
2B = 11
3C = 13

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Quick Questions

1. What denary value does the hex digit B represent?
A. 11 ✓
B. 12
A=10, so B=11. The letters count up from A=10 to F=15.
2. Which is the largest single hexadecimal digit?
A. 9
B. F (15) ✓
Hex goes past 9 using letters, and F=15 is the largest single digit.
3. Which of these is a valid hexadecimal digit?
A. G
B. E ✓
Hex only uses 0-9 and A-F. G is not a hex digit.
4. How many different digits does hexadecimal use?
A. 16 ✓
B. 10
Hex is base 16: the digits 0-9 plus the six letters A-F make 16 digits.
5. How many bits does one hex digit stand for?
A. 4 bits (one nibble) ✓
B. 8 bits (one byte)
Each hex digit matches one 4-bit value, from 0000 to 1111.

Match the Pairs

C → The hex digit C, which stands for the denary value 12
F = 1111 → F is the largest single hex digit: denary 15, which fills one 4-bit value
Hexadecimal has 16 digits, counting from 0 to 9 and then A to F → 0123456789ABCDEF
The letter D stands for 13 in hexadecimal → D = 13
A = 11 → A is worth 10, not 11. B is 11. The letters start at 10 and go up in order to F=15.
G = 16 → G is not a hex digit. Hex stops at F=15, because it has only 16 digits (0 to 15).

Key Term

0123456789ABCDEF
The 16 hex digits: 0-9, then A=10, B=11, C=12, D=13, E=14, F=15. Each digit stands for one 4-bit value, and F (15) is the largest single hex digit.

Fill in the Blanks

1. Hex digit A = 10 in denary
Hint: Type the denary value that the letter A stands for.
2. The largest single hex digit is F
Hint: Type the letter for the highest single hex digit, worth 15.
3. Denary 13 is written as hex digit D
Hint: Type the hex letter that stands for denary 13.
4. Hex digit F = 1111 in 4-bit binary
Hint: Type the 4-bit binary value that matches the largest hex digit.
5. Each hex digit stands for 4 bits (a nibble)
Hint: Type how many bits one hex digit represents.

Spot the Error

Question 1
A A = 10
B B = 11
C C = 13
D D = 13
Line C — In hexadecimal C stands for 12, not 13. D is 13. The letters go A=10, B=11, C=12, D=13, E=14, F=15.
Question 2
A F = 16
B E = 14
C D = 13
Line A — F is worth 15. Hex has 16 digits but they run from 0 to 15, so no single hex digit is worth 16.
Question 3
A h = "0123456789ABCDEF"
B print(h[11]) # A
C print(h[15]) # F
Line B — Counting from 0, h[10] is A. h[11] is B, so the index should be 10 to match the comment.
Question 4
A # each hex digit = 4 bits
B A = 1001
C F = 1111
Line B — A is 10 in denary, which is 1010 in binary. 1001 is 9.
Question 5
A 0 = 0000
B 9 = 1010
C F = 1111
Line B — 9 is 1001 in 4-bit binary (8 + 1). 1010 is 10, which is the hex digit A.

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