Rich G. answered 06/27/18
Tutor
5.0
(142)
Adjunct instructor, IXL video contributor
It's really low, that's why it's the highest ranked hand in poker.
The number of possible 5 card combinations in a deck of cards is
52C5 = 52!/5!(52-5)! = 52!/(5!*47!) = 2,598,960 possible combinations
There are only 4 possible combinations of a royal flush
So the odds of being dealt a royal flush is
4/2,598,960
= 1.539 * 10-6
Or 1 out of 649,740