The FACTORIAL function returns an integer that is the factorial of argument-1. The type of this function is integer.
Usage
FUNCTION FACTORIAL (argument-1)
Parameters
Argument-1 must be an integer greater than or equal to zero.
Returned Values
1. If the value of argument-1 is zero, the value of 1 is returned.
2. If the value of argument-1 is positive, its factorial is returned.