It's mostly just experience to be honest. I have played over 10 million hands of poker. I don't need to "do the math" for 99% of common spots because I have seen them so many times and I already know what the right play is.
Sometimes I think the odds are in the poker calculator. But this is more an exception than the rule. The right decision most often comes to mind the very first, I try to stick to it. In order to keep yourself in good shape you need to constantly work on your game.
There are already calculated values collected in the table, where everything is simple and clear. They can be printed out and look at them playing. Over time, this information remains in memory.
