This is a discussion on Odds within the online poker forums, in the Learning Poker section; Odds are not a difficult concept to understand, but some players seem to think, that because they have two chances to improve after the flop, 


#1




Odds
Odds are not a difficult concept to understand, but some players seem to think, that because they have two chances to improve after the flop, the odds should be halved. Unfortunately this is not the case as a couple of examples will show. As everybody and their dog knows, that if you have suited hole cards and two of the same suit show up, the odds of making a flush are 4.22/1 usually rounded to 4/1. The turn doesn't help you and now 9 cards out of 46 can help you, odds of 4.11/1, still 4/1. Another hand and you have an outside straight draw. The odds of making it are 4.875/1 (rounded to 5/1) on the turn and 4.75 on the river. So the chances of improving on the turn and the river are to all purposes identical. Work out others if you wish. Strangely enough, when you hold suited hole cards the odds of one matching card turning up on the flop is 7/2

#2




Odds and pot odds are simple, but reverse implied odds is a bit complicated in 10s decision. I use for odds factor 2 to turn......Phil Gordon 4/2 rule pressumed no river.

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On the flop = number of flush outs x 4 = (134)x 4 = 36% On the turn = number of flush outs x 2 = (134)x 2 = 18% 
#4




re: Poker & Odds
Not to beat a dead horse but I don't understand the math you are using here. If you are just looking at one card to come then the odds don't change much that is true, however, if you compound the odds of the turn and the river then the result is close the the 36% that the 2 and 4 shorthand gives you.

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On flop, you would only multiply by 4 if you were guaranteed to see the river card. This is when a player is all in and there is no more betting. Since there is no more betting, you can calculate your probability of hitting on the turn or river. If there is a chance of future betting on turntoriver, then you multiply by 2 since you need to calculate the probability of hitting on the turn, then on the river if you miss. So, is there any more betting after flop? Yes: outs x 2. No? Outs x 4. 
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#7




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I think too many people get stuck at looking at a hand being played out one way (though sometimes less than that) and then get lost when the board or opponent doesn't cooperate. 
#8




re: Poker & Odds
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The rule of 4 is the probability of hitting on the turn or river. The key word being 'or'. When a player is allin, we can use this rule since we are guaranteed to see both the turn and river. However, if we calculate the probability of hitting on the turn or river when there is a chance of future betting, we are giving ourselves false a false probability to hit since it isn't guaranteed you'll see the river if you miss the turn. Lets say you have a flush draw and have 9s outs. Let look at a few scenarios. 1. The pot is $50 and your opponent bets $25 and is all in. You have to call $25 to win a pot of $75.. If you do the rule 4, you have a ~35% chance to hit your hand or 1.86:1 odds of hitting. We already know it's a +EV call since the pot odds > hand odds, but if we plug this into an EV formula, we get: EV = [$won x .35]  [$lost x .65] EV = [$75 x .35]  [$25 x .75] EV = [$26.25]  [$16.25] EV = $10 This means that, if you play this scenario out over a large sample size, you'll average $10 per hand. 2. Now lets say the opponent isn't allin. You do the rule of 4, but miss the turn. On the turn, opponent bets out pot ($100) and you fold. Since you fold and didn't see the river, when we plug it into the EV formula, we have to make adjustments since you only saw the turn and not the turn+river. The odds of hitting your out on the turn is ~19% EV = [$won x .19]  [$lost x .81] EV = [$75 x .19]  [$25 x .81] EV = [$14.25]  [$20.25] EV = $6 This means that, if you play this scenario out over a large sample size, you'll average $6 per hand. 3. Same as scenario 2, but this time you call the $100 bet to win a pot of $200. You have a ~20% to hit your out on the river. If we plug this into the EV formula we get: EV = [$200 x .20]  [$100 x .80] EV = [$40]  [$80] EV = $40 You're still losing money. 4. Same as scenario 2, but villain bets out $25 on the turn. You have call $25 to win a pot of $125. If we plug this into the EV formula, we get: EV = [$125 x .20]  [$25 x .80] EV = [$25]  [$20] EV = $5 This looks like it's a +EV call, but remember you're still losing $6 on the turn. So, even if this is a +EV call, you're still $1 over the long run in for both situations. The only way you would break even after making the EV call in scenario 2 is your opponent bet out $23 on the turn and you had to call a bet of $23 to win a pot of $123. When plugged into the EV formula we get an EV of +$6 + ($6) = 0. If they bet any less, then calling would be +EV. Now, you might be wondering "What if, in the 2nd scenario, I call and hit the turn? Doesn't that mean anything?" The answer is 'no'. Even if you hit your flush on the turn, we still calculate using the rule of 2 for the probability of hitting on floptoturn. Even if you hit the turn, the call is still EV and you're losing money in the long run. In poker, it's about making +EV decisions. It doesn't matter if you hit your draw, if it's a EV call, you're losing money. I hope this all makes sense. 
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#10




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However, it's impossible to know when an opponent will bet or check on the turn [if they have those options] and it's better to side with caution and calculate it as if they will bet the turn. 