It would seem that 4 of a kind would be harder to get than a straight flush. After all there are only 13 different numbered cards in a deck. Yet it is more likely that you should be dealt 4 of a kind than a straight flush. The reason is, you only need 4 cards to make up four of a kind and you have five chances to get them. For more information you get reference from here
http://www.casinosdiary.com/