Question

If $A=\{1,2,\{3,4\left\}\right\}$, then the number of elements in $P\left(P\right(A\left)\right)$ is
(where $P\left(A\right)$ is the power set of $A)$

Answer 1

$A=\{1,2,\{3,4\left\}\right\}$
$n\left(A\right)=3\therefore n\left(P\right(A\left)\right)=2^3=8\therefore n\left(P\right(P\left(A\right)\left)\right)=2^8=256$