In how many ways can a pack of 52 cards be formed into 4 groups of 13 cards each?
Here order of group is not important, then the number of ways in which 52 different cards can be divided equally into 4 groups is 52!4!(13!)4
Alternative method: Each group will get 13 cards. Now first group can be given 13 cards out of 52 cards in 52C13 ways. Second group can be given 13 cards out of remaining 39 cards (i.e. 52-13=39) in 39C13 ways. Third group can be given 13 cards out of remaining 26 cards (i.e., 26-13=13) in 13C13 ways. But the all(four) groups can be interchanged in 4! ways. Hence the required number of ways
=52C13×39C13×26C13×13C13×14!
=52!13!39!×39!13!26!×26!13!13!×1×14!
=52!(13!)44!