Quote:
Originally Posted by TheShakeDaddy
How did you come up with 55%, 20% & 40% for the TT
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Using any equity calculator, you know that TT vs two overcards is approxiately 55% (not exactly, as it differs slightly based on card rank, suitedness, and connectedness...but you are really trying, at best, to estimate, not get exact numbers).
You will also see that TT vs an overpair has only a 20% chance of winning.
So, to calculate your equity against villains range, you average the equity against all possible hands in the range
This is where combinitorics comes in.
So, you first figure out how many combinations of overcards there are. The easiest way for me to visualize this is to say (to make AK, there are 8 cards (4 aces and 4 kings) that you can draw to make AK, and then if you draw one of those 8 cards, there are 4 other cards (either 4 aces if you drew a King, or 4 kings if you drew an Ace for your first card) to make AK. Therefore there are 32 (8*4) possible permutations that make AK or KA. Since order doesn't matter, and AK is equivalent to KA, we divide that number by 2, so there are 16 combinations that make AK).
You do the same for pocket pairs and see that for any specific rank, there are 6 combinations (take Aces for example. For your first card, there are 4 aces, for your second card, there are three aces. That means 12 possible permutations. Again, divide by 2, and you have 6 possible combinations)
Since we said that villains range was AQ+, JJ+, below is a table of possible holdings, and the number of combinations, and their approximate equity
Hand Combos Equity
AA 6 20%
KK 6 20%
QQ 6 20%
JJ 6 20%
AK 16 55%
AQ 16 55%
Total 56
Using the numbers above, you can do a weighted average (average=(# of instances*value of instance)/(total number of instances). This yields a value of 40%.
So, based using combinations, you estimate that the equity of your pocket tens versus his range of AK, AQ, AA, KK, QQ, and JJ is approximately 40%, and you make your calling decisions based on whether or not you have positive EV for your call based on that number.
As mentioned above, this is not terribly easy to do on the fly. It is best to do this calculation on paper (or with excel) a few times so you understand how it works and develop a feel for the mechanics. Then download an equity calculator and start modelling common situations.