Base 16
number system, which consists of symbols 0-9 and A-F. It is a useful system in
computers because there is an easy mapping from 4
bytes to a single hex digit. Thus one can represent every
byte as a two consecutive hexadecimal digits.
For example:
0001 = 1
0010 = 2
0011 = 3
0100 = 4
...
1010 = 10
1011 = A
...
1111 = F
So the the binary representation for 79 (0100 1111) can be written as 4F.
Hex is an abbreviation of Hexadecimal.
So the counting is as follows: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F, 10, 11, .. 19, 1A, 1B, ..., 1F, 20, ..., 9F, A0, ...
In texts there are several ways to denote hexadecimal numbers. One (derived from C) is to start with '0x'. Another way (from Pascal) is to end the numbers with a 'h'. So, 20h is the same as 0x20, which equals 32 in [decimal counting]?.
The word "hexadecimal" is strange in that "hexa" is derived from Greek and "decimal" is derived from Latin. The original term was the fully-Latin "sexidecimal", but that was changed because some people thought it to be too racy.
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