Quote Originally Posted by Santo2True View Post
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so for example, we hold KTo and there is OESD on the flop as it comes
QJ6r

Open Ended Straight Draw = 8 Outs (4 Aces and 4 Nines)
King Top Pair = 3 Outs (4 Kings less the King in our hand)

Total Outs = 11 Probability of Winning = 11 x 4 = 44%

Lets say the pot on the flop =$40

Total Pot is now $40 and we are asked to call $10 so our Pot odds are 4 to 1 and our break even % = 100% divided by 5 = 20%.

which gives us (44% vs 20%) so in this example it will be a "correct" call and in the long run a "profitable" call

That's just the simple math I use and it might look crazy at first, but the more you use it the easier it gets and soon you will keep all the numbers in your head and be able to do them on the fly. GL
The 4x rule is used for a shove or limit (I think) because in no limit there will usually be another bet on the turn and you have to reevaluate again.

For the turn or river just use 2x+1. And don't for get about implied odds.