[MRBAA]

Say you have a pair of sevens in the hole, full game, no other sevens showing. Two other players call the bring in, and you do, too. Four of you see fourth street and the boards are as follows:

(77)95
(xx)J2
(xx)3K
(xx)A8

The player with the ace bets, both other players call and you call, too.

On fifth street, the boards are as follows:

(77)953
(xx)J28
(xx)3KT
(xx)A84

No one is suited. Now the ace bets again and both opponents fold. You are considering whether to call or fold. There are two unseen sevens that can significantly help your hand, as well as the chance of making a second pair.

So you count the cards you've seen -- ten on third street (seven opponent up cards and your three cards), four more on fourth and four more on fifth, for a total of 18 cards you've seen. But what about the unseen cards your opponents hold? Given the action so far, it's very likely that for each of the three at least one of their down cards was NOT a seven -- since they all made or called a bet on fourth and a seven would not have helped their hand. Discounting the unlikely chance one of your opponents also had pocket sevens, you decide to count three more "seen" cards -- the three non-sevens of your opponents' down cards -- bringing the total of "seen" cards to 21. You now use that number to calculate your chances of spiking a seven, making those odds <15-1 against on one card, rather than >16-1. Good thinking or over-reaching?