Pot Odds after the flop

[jaundice]

I'm pretty new to hold'em and I'm trying to learn to play better for local high school home games. I just read the Lee Jones book, and I'm having a little trouble implementing the idea of pot odds. For example, say I have 4 to a flush or open ended straight after the flop. There are 9 cards that can give me the flush, or 6 that can give me the straight, about 17/47 odds. A couple of questions:

1) How do you determine the odds for two cards? I should have learned it in math, but oh well.
2) Do you bet the hand before the turn as if the odds were for both of the cards, or as if you were taking the odds one card at a time?

If there are any errors with my slang or ideas, please correct them. Thanks!

[Nottom]

OK, first if you have a flush draw + a straight draw you have 15 outs not 17, which means 15 out of the remaining 47 cards will make your hand and 32 that don't.

To express this as odds you should say your odds are 32:15 against or can reduce it to 2.13:1. This is the number you need to compare to the pot in order to see the next card.

OK now back to your questions.
1) The easiest way to figure your odds for 2 cards is to figure the odds of missing twice then subtract that from 1.

For example, you have a 4 flush so you have 9 outs. this means you have 9/47 of catching on the the turn and if you miss there have 9/46 to catch on the river. To get the odds of catching you should first figure the odds of missing.

38/47*37/46= 0.65, so the chance of catching are 0.65:(1-0.65) or 0.65:0.35 or about 1.86:1


2) You should normally only look at the odds to complete on the next card when you are drawing. The obvious exception to the rule often comes up in NL when either you or your opponent would be all-in after the flop. Ex) If there is a $100 pot and your opponent bets $100 but you only have $50 left, you are getting 3-1 on your call and don't have to worry about calling a turn bet if you miss so you can use the odds with 2 cards to come to decide if you want to call.

The other time you can worry about the odds of catching by the river are for value bets and raises on the flop.

One of the more common ones is when you have a good flush draw and are in a multiway pot. If you can anticipate getting more than 2 callers on a bet or raise, then you should make that bets since your odds of hitting are just under 2:1. This means if you get 3 people calling you bet, you are making money on every dollar that you put in the pot since you are getting 3:1 on a 2:1 shot.

The other somewhat less common example is when you have an openended straight-flush draw. This gives you 15 outs and actually makes you a slight favorite over top-pair to win by the river. In this case your main concern should be trying to maximize the amount of money going into the pot on the flop.

Other than these value-betting situations that arise from time to time, its important to remember that pots odds are used for calling ... not betting. Most of the time you would rather see the river as cheaply as possible when on a draw. I see nonsensical statements like the following all the time:
"I decided to raise with my 22 from the blind with 5 other players already in becasue I was getting 11-1 on my bet and am only 7.5-1 against flopping my set."

This makes no sense. If you have the option of taking a free card you are getting infinate odds to see a card, by betting here you are only getting 5-1 on your bet if everybody calls, which makes it a poor bet since your odds of catching your hand are only 7.5-1.

[jaundice]

First, thanks for the great explanation. But, I didn't understand this part.

[ QUOTE ]
2) You should normally only look at the odds to complete on the next card [after the flop] when you are drawing.

[/ QUOTE ]

I didn't quite catch the reason behind this. I would have thought that it would be better to try and figure out the risk and approximate pot size for the next two cards. Could someone explain the reason for not calculating the pot odds for both the turn and river cards on a draw?

[Nottom]

Because you are going to have to put more money in on the turn when you miss. If you constantly put money in using the wrong odds it will catch up with you.