If a set A and n elements then find the number of elements in its power set

The power set of set A is a collection of all subsets of A.

For example: if the set A is {1, 2} then all possible subsets of A would be {} (empty set), {1}, {2}, {1, 2}

Hence powerset of $A$ that is $P(A)$ will be $\{\phi,\{1\},\{2\},\{1,2\}\}$

Now if the number of elements in set $A$ is $n$ then the number of elements in power set of A $P(A)$ is $2^{n}$