Rule of 2 and 4
What it means
A quick count to turn outs into a probability: outs × 2 for one card and outs × 4 for two cards (flop to river). The rule of 4 applies when you will see both cards, for example with an all-in on the flop; if your opponent can bet again on the turn, use the rule of 2. With many outs, the rule of 4 gives more than the full count.
Example
Flush draw on the flop: 9 outs × 4 = 36% by the river (full count: 35.0%). On the turn: 9 × 2 = 18% (full count: 9 / 46 = 19.6%). With 15 outs, 15 × 4 = 60%, against 54.1% from the full count.
Also called: Regla del 4 · Regla del 2 · Regla del 2 y 4 · Rule of 4 · Rule of 2
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