This document discusses the hexadecimal number system. It uses base 16, with digits 0-9 and letters A-F to represent values. Hexadecimal is important in computing because it connects decimal, binary, and color/coding systems. It allows counting beyond decimal 9 by replacing 9 with A, B, C, etc. up to F, at which point the next place value increases like a standard positional number system.

1. Hexadecimal Base-16
Unit 7.2

2. Learning Outcomes
• To understand that hexadecimal uses letters
as well as numbers
• To be able to make connections between
hexadecimal and binary number systems

3. Base 16
The hexadecimal number systems uses a base of
16. However, not all of the symbols used for this
system are digits.
The symbols used in hexadecimal are:
Digits: 0 – 9
(0,1,2,3,4,5,6,7,8,9)
Letters: A – F (A,B,C,D,E,F)
This is a positional number system.

4. Counting in Hexadecimal
Counting in hexadecimal can be confusing. In
decimal the number 10 is means that there are
no units but one ten. But in hexadecimal it is
written as A.
Instead of replacing the nine with a zero and
putting a one in front of it we use the letter A a
digit.

5. Decimal
Hexadecimal
Decimal
Hexadecimal
Decimal
Hexadecimal
1
1
11
B
21
15
2
2
12
C
22
16
3
3
13
D
23
17
4
4
14
E
24
18
5
5
15
F
25
19
6
6
16
10
26
1A
7
7
17
11
27
1B
8
8
18
12
28
1C
9
9
19
13
29
1D
10
A
20
14
30
1E

6. Importance of Hexadecimal
The hexadecimal number system plays an
important role in computing along with binary.
Binary or base 2 is what computers understand
to make the work.
Hexadecimal is used for colours and coding on a
computer. For example:
color = “#FF