In some of the online poker apps they show winning percentage - which I interpret as chances of winning. How to calculate that - I understand that it is based on combinatorics. Suppose at Flop I have to find the winning percentage. At Flop 2 community cards are yet to appear. Suppose there are 6 players. None of them has folded. Each player has been dealt 2 hole cards. So I know what these 12 cards are. I know 3 community cards. Totally 15 cards are known to me. Rest of the 2 community cards could be chosen from 52 - 15 = 37 cards.