Question

The number of sunsets that can be created from the {1,2,3} is

Answer 1

The formula is $2^{number of elements }$ in the set. This set {1,2,3} has 3 elements, so the number of subsets is gotten by substituting 3 for the number of elements in the set: 2number of elements in the set = $2^{3}$ = 2x2x2 = 8.  So there are 8 subsets. They are: 
 1. { } or ∅, the empty set, sometimes called the "null" set.
 2. {1}
3. {2}
4. {3}
5. {1,2}
6. {1,3}
7. {2,3}
8. {1,2,3}.