How do people work out Ev to such an exact extent??

[SquirrelJ]

I keep reading various posts on this form and see things that I just don’t understand. So was after a little bit of help please.

villain is 36/19/5

What and where do these people get these figures from??? Do I need to start using this if I want to be a better player a more profitable player???

Ev +

Sometimes i see posts where people say yes you should call you have positive Ev. Now I understand that this means in the long run you will win money if you make this decision.

However I have seem people work this out after saying I think he would only raise with these sort of hands like big pairs and Ak Aq and then work out a percentage as to what he might have and their chances of winning. Now on earth do you work this all out in 10 seconds.

Is it possible to be so accurate with your Ev estimations???

How do successful players work out when to call or fold in difficult situations???