## factorial

(mathematics) The mathematical function that takes a natural number, N, and returns the product of N and all smaller positive integers. This is written

N! = N * (N-1) * (N-2) * ... * 1.The factorial of zero is one because it is an empty product.

Factorial can be defined recursively as

0! = 1 N! = N * (N-1)! , N > 0The gamma function is the equivalent for real numbers.

For example, the number of ways of shuffling 52 playing cards is 52! or nearly 10^68. *52 Factorial*.

Last updated: 2012-11-23

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