Don't be worried before taking this lesson that it is going to involve very complex maths, as its not going to. EV calculations are impotant in poker, as they lead us to making the most optimal play at any given time by analysing the situation we are faced with. Instead of thinking: "we are ahead or behind", we analyse the percentages and probability that the situation presents us with, this enables us to make the best play with our hand at any given time! This can be expressed by the following formula:
Total Amount of Money in the pot (including our call) / % of the time we win = Our Expected Value
In terms of the: % of the time we win; we can use the 'Two Times Four Times' rule to give us the rough % chance of Winning the hand.
First we need to calculate our 'outs', we then take this number and if we are on the flop multiply it by 4 to give us the rough percentage chance of hitting our hand by the river.
For example; if we hold 45 and have a flush draw on a 7jA flop, any of the following 9 cards in the deck will give us a flush:
We therefore have 9 outs to make our flush. We then multiply 9 by 4 to give us 36, this is the rough percentage chance that we will hit our hand by the river. On the turn (with one card to come) we count our 'outs' again and multiply by 2 to give us the rough percentage chance of hitting.
This equation for calculating the chances of hitting outs can be expressed more clearly as:
Number of outs * 4 (if we are on the flop)= our rough percentage chance of hitting by the river.
Number of outs * 2 (if we are on the turn)= our rough percentage chance of hitting by the river.
In our example if we are trying to calculate our chances of hitting our flush on the flop it would be caluculated like this:
9 * 4 = 36%
On the turn we would calculate our chances of hitting our flush as follows:
9 * 2 = 18%