Perhaps you should run the program to find out.
Here is the definition of N factorial:
N Factorial == N! == N * (N-1) * (N-2) * (N-3) * . . . 4 * 3 * 2 * 1
N must be a positive integer or zero, and 0! is defined to be 1. For example,
6! == 6 * 5 * 4 * 3 * 2 * 1 == 720
Let us write a program that computes N! . The program checks that N is positive or zero, then computes the factorial.
Say that the user enters a 5. How can the program generate the integers 5, 4, 3, 2, and 1 that are to be multiplied?