Power set of a set is the set of all possible sets formed by elements of the given set.
Given set B = { 1 , 2 , 3 }
Power set P(B) = { 1 , 2 , 3 , ( 1 , 2 ) , ( 2 , 3 ) , ( 3 , 1 ) , ( 1 , 2 , 3 ) , Ø }
Number of elements in set = n(B) = 3 .
Therefore, Number of elements in power set = 2^n(B) = 2^3 = 8 .