number of ways you can select  n=5  elements from  N=9  elements.

It's just C(9,5) = 9! / [(9-5)! * 5! ] = 9! /[4! * 5!] = [9 x 8 x 7 x 6] / [ 4 x 3 x 2 x 1] =

[3 x 2 x 3 x 7] = 126 ways