factorial

factorial (fækˈtɔːrɪəl)
—n
1.	the product of all the positive integers from one up to and including a given integer. Factorial zero is assigned the value of one: factorial four is 1 × 2 × 3 × 4. Symbol: n!, where n is the given integer
—adj
2.	of or involving factorials or factors
fac'torially
—adv

factorial

factorial   (fāk-tôr'ē-əl)  Pronunciation Key  The product of all of the positive integers from 1 to a given positive integer. It is written as the given integer followed by an exclamation point. For example, the factorial of 4 (written 4!) is 1 × 2 × 3 × 4, or 24.

factorial definition

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 > 0
The gamma function is the equivalent for real numbers.
(2005-01-07)