When A = Φ then the number of elements in P(A) is ___________
Given:
\[ A = \Phi \]
The empty set contains no elements. Therefore,
\[ n(A) = 0 \]
The number of elements in the power set of a set having \(n\) elements is:
\[ 2^n \]
So,
\[ n(P(A)) = 2^0 = 1 \]
Answer
\[ \boxed{1} \]