In this problem, we will use the combination formula. Combination
is where the order of the things doesn’t matter.
So the formula for this problem is:
n! divided by r! (n-r)! = n/r
where:
n is the number of things to choose from and we choose r of
them
11C2 = 11! /
[2! (11 - 2)!]
= 11! / (2! * 9!)
= 55
