If a card is drawn from a pack of cards then the probability of selecting a club card or king card is

The random experiment is picking a card from the deck of 52 cards

$n\left(S\right)=52$

Let $A$ be the event of getting a club or a king card

$n\left(A\right)=13 clubs+4 kings-1 club king=16$

Therefore, the required probability is 

                                 $\begin{array}{rcl}P\left(A\right)& =& \frac{n\left(A\right)}{n\left(S\right)}\\ & =& \frac{16}{52}\\ & =& \boxed{\frac{4}{13}}\end{array}$