It folds to you on the button with T♠9♠ after a middle-position raise - a hand that flops plenty of draws.
Opener makes it 600 (3 BB); you hold T♠9♠ on the button. Best?
WhyA suited connector against a lone raiser is a comfortable flat in position - it flops the kind of draws you can price precisely once the pot grows.
What happensYou call and the blinds fold, and now you get to put the rule of 2 and 4 to work. Pot: 1,500 (7.5 BB).
Flop
Flop: 8♦ 7♣ 2♥ - you flop an open-ended straight draw (any 6 or J), eight outs. He bets 900, so you call 900 to win 2,400 (~2.7-to-1, need ~27%).
Use the rule of 2 and 4 to estimate your equity, then compare to the price.
WhyEight outs with two cards to come is about 32% by the rule of four, and the price only asks for roughly 27%, so you're ahead of it. Just note you'll switch to the rule of two - outs times two - the instant the turn peels and one card is left.
What happensYou call, priced in by two cards' worth of equity. Pot: 3,300 (16.5 BB).
Turn
Turn: K♣ - a brick. Now only one card to come. He bets 2,400, so you call 2,400 to win 5,700 (~2.4-to-1, need ~30%).
Rule of 2 now: eight outs × 2 ≈ 16%. Facing this price, best?
WhyOne card to come cuts the same eight outs to about 16% by the rule of two, but the turn price still demands around 30%, and with stacks this shallow there's little future money to make up the difference. A draw that was a fine flop call is now a losing turn call - the equity halved and the price didn't budge.
What happensYou fold. The math flipped on the turn, and so did you.
The rule put you near 32% on the flop (a call) and about 16% on the turn (a fold). Same eight outs, half the value, opposite decision - the second card to come is everything.
Multiply outs by four on the flop and by two on the turn to estimate equity - and redo the count every street, because a draw with one card left is worth half what it was with two.