In how many ways can a pack of 52 cards be diuided into 4 sets, three of them having 17 cards each and the fourth just one card ?

First we divide 52 cards into two groups of 1 card and 51 cards. This can be done in $\frac{52!}{51!1!}$ ways. Now, everv group of 51 cards can be divided into 3 groups of 17 cards each in $\frac{51!}{(17!{)}^{3}3!}$

$\therefore$ Num er o ways $=\frac{52!}{51!1!}\times \frac{51!}{(17!{)}^{3}3!}=\frac{52!}{(17!{)}^{3}3!}$