calculating odds...

[djhoneybear]

I understand how to calculate the odds in most situations (i.e. making trips on the flop, drawing to a four flush on the turn etc.). What I'm not clear on is how to calculate odds that are more complex. How do I calculate two pairing my hole cards on the flop or making a strait with a three card straight draw after the flop.

[Cobra]

I feel the easy way to do these is by using combinations. Assume that you have JT and you want to know the probabilities of getting two pair.

There are 50 unknown cards
There are 3 Jacks and 3 Tens
There are 44 other cards not JT.

Probability of two pair is 3*3*44/combin(50,3)=2.02%

You choose a Jack in one of three ways, a Ten in one of three ways, and any of the other 44 cards. You devide by the total combinations of flop of 50 cards.

If you wanted to figure out the possibility of getting a straight you can get a straight if you flop the following.
AKQ, KQT, Q98, 987. You multiply the probability of getting any one of these by four since there is four terms.

=4*(4*4*4)/combin(50,3)=256/19600=1.3%

Cobra