Texas Hold'em Poker Runner-Runner (Backdoor) Odds
When it takes two perfect cards on both the turn and the river to covert an average or weak hand after the flop to a strong one, this should normally qualify as a "long shot". Also, "strong" hands are considered here to be straights and better. These are often referred to as "backdoor" hands such as a backdoor straight or flush etc.
After the flop, there are always 47 unseen cards. These will make a total of 1081 possible two card combinations that are used to make these probability comparisons.