Find the number of subsets of the set {1,2,3,4,5,6,7,8,9,10,11} having 4 elements.

Here the order of choosing the elements doesn’t matter and this is a problem in combinations.

We have to find the number of ways of choosing 4 elements of this set which has 11 elements.

This can be done in 11 $C4$ ways = 330 ways