how to determine the number of sub-set in a particular set?

Answer 1

2^n where n is the number of elements in the set
eg; {1,2,3,4,} will have 2^4 subsets which is 16 subsets

Answer 2

If a set has n members, the number of subsets (including the set itself and the empty set) is given by 2^n.

Answer 3

If your set has n items, the possible subsets have:

n items, and this can only happen one way;
n-1 items, and this can happen in nC(n-1) ways;
n-2 items, and this can happen in nC(n-2) ways;

...

1 item, and this can happen in nC1 ways;
0 items (the empty set is a subset), which can happen in 1 way.

I believe this sums to 2^n + 1?