What is factorial in math?
In mathematics, the factorial of a non-negative integer n,
denoted by n!, is the product of all positive integers less than or
equal to n. For example,
5!=5x4x3x2x1=120
The value of 0! is 1, according to the convention for an empty
product.
The factorial operation is encountered in many different areas
of mathematics, notably in combinatorics, algebra and mathematical
analysis. Its most basic occurrence is the fact that there are n!
ways to arrange n distinct objects into a sequence (i.e.,
permutations of the set of objects). This fact was known at least
as early as the 12th century, to Indian scholars. The notation n!
was introduced by Christian Kramp in 1808.
The definition of the factorial function can also be extended to
non-integer arguments, while retaining its most important
properties; this involves more advanced mathematics, notably
techniques from mathematical analysis.