8 (eight) is the
natural number following
7 and preceding
9.
In mathematics
8 is:
* a
composite number, its
proper divisors being , , and . It is twice 4 or four times 2.
* a
power of two, being 2 (two cubed), and is the first number of the form , being an integer greater than 1.
* the first number which is neither
prime nor
semiprime.
* the base of the
octal number system, which is mostly used with
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
s. In octal, one digit represents three
bit
The bit is the most basic unit of information in computing and digital communications. The name is a portmanteau of binary digit. The bit represents a logical state with one of two possible values. These values are most commonly represented a ...
s. In modern computers, a
byte is a grouping of eight bits, also called an
octet.
* a
Fibonacci number, being plus . The next Fibonacci number is . 8 is the only positive Fibonacci number, aside from 1, that is a perfect cube.
* the only nonzero
perfect power that is one less than another perfect power, by
Mihăilescu's Theorem.
* the order of the smallest non-abelian group all of whose subgroups are normal.
* the dimension of the
octonions and is the highest possible dimension of a
normed division algebra.
* the first number to be the aliquot sum of two numbers other than itself; the discrete biprime , and the square number .
A number is divisible by 8 if its last three digits, when written in
decimal
The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers of the Hindu–Arabic numeral ...
, are also divisible by 8, or its last three digits are 0 when written in