Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.In poker, the probability of each type of 5-card hand can be computed by calculating the proportion of hands of that type among all possible hands. The royal flush is a case of the straight flush. It can be formed 4 ways, giving it a probability of 0.000154% and odds of 649,740 : 1. When ace-low straights and ace-low straight flushes are not counted, the probabilities of each are reduced: straights and straight flushes each become 9/10 as common as they otherwise would be. The 4 missed straight flushes become flushes and the 1,020 missed straights become no pair.