The number of non-empty subsets of the set $\{1, 2, 3, 4\}$ is
Write the following sets in roster form :
$C = \{ x:x{\rm{ }}$ is a two-digit natural number such that sum of its digits is $8\} $
Consider the sets
$\phi, A=\{1,3\}, B=\{1,5,9\}, C=\{1,3,5,7,9\}$
Insert the symbol $\subset$ or $ \not\subset $ between each of the following pair of sets:
$A, \ldots B$
Write the following intervals in set-builder form :
$\left[ { - 23,5} \right)$
How many elements has $P(A),$ if $A=\varnothing ?$