## composite numberA positive integer that can be factored into smaller positive
integers, neither of which is one. If a positive integer is not composite
(4, 6, 8, 9, 10, 12, ...) or one, then it is a prime
number (2, 3, 5, 7, 11, 13, 17, ...). As Karl Gauss
put it in his Disquisitiones Arithmeticae (1801): "The problem
of distinguishing prime numbers from composite numbers and of resolving
the latter into their prime factors is known
to be one of the most important and useful in arithmetic." One reason it
is important today is that many secret codes and much of the security of
the Internet depends in part on the relative difficulty of factoring large
numbers. But more basic to a mathematician is that this problem has always
been central to number theory. Numbers that, for their size, have a lot of factors are sometimes referred to as highly composite numbers. Examples include 12, 24,
36, 48, 60, and 120. ## Related category• TYPES OF NUMBERS | |||||

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