How many subsets of the set {1,2,3,4,5,...,10} contain the number 5?
The number of total subsets = 2^10 = 1024 (including the empty set)
The number that DON'T contain "5 " = 2^9 = 512 (including the empty set)
So....the number that DO contain "5" = 1024 - 512 = 512
