Hey Wildcard, welcome! First of all, don't take it personally; sometimes people will take a peek and won't answer for whatever reason. It happens.
In this case though, I think maybe it has to do with the fact that your question is a bit broad and lacking in detail, so people aren't quite sure how to answer. The reason being that there's a great deal that goes into calculating odds (pot odds, implied odds, outs, etc.), possibly much more than you are expecting, and more than could ever be covered in a single post. I highly suggest you take a look at some of the great sections in Cardschat's Strategy Articles
. I'm sure you'll find what you're looking for right away.
To get you started though, a quick and easy formula I learned recently is the x2+1 rule. I can't quite remember where I saw it, but it gives you a rough (off by a couple of percentage points depending on the number) estimate of your chances of catching your outs (or the cards that would improve your hand). You just take the number of outs, multiply by 2, and add 1.
For example, lets say you have AhKh and you're looking at a board of 3h10s8h. There are at least four hearts out there (the two in your hand and the two on the board) and just need one more to give you the nut flush. If there are 13 hearts in a deck, that means that there are 9 hearts left in the deck; in other words 9 outs. In addition, we could also assume that any Ace or King would also improve your hand. If you have one of each, then there's 3 of each left; another 6 outs. Meaning you have a total of 15 outs. (Yes, your opponents might have any one of them, or it might have been a burncard; but there's no way for you to know that, so when you're calculating outs you just go by what you know for certain).
So if you have 15 outs, just multiply by 2 and add 1=31. Meaning you have approximately a 31% (or 3:1) chance of getting a card that would improve your hand on the turn. Basically double that for the river.
The real question however, is how does this help you? That's where pot odds
comes in. Pot odds is basically a comparison of the amount of money you have to put into a pot in order to win it. If the pot is currently $100, and you have to call $30 in order to see the next card, then your pot odds are roughly 30% (or around 3:1). If your pot odds are equal or less than your odds of hitting an out, then it is "mathematically correct" for you to make the call.
What does mathematically correct mean? It means that if you were to play the exact same hand a million times the exact same way, over THE LONG RUN, you would end up a winner. Of course, in this game or the other you might get sucked out on (after all, you are 3:1 to hit your card, not 100%), but in the long run you will win. And the no. lesson in poker is that it is the long run that counts, not the short term.
Of course, in practice there's SO MUCH more to take into consideration than just these two factors, that I will outright say DO NOT take what I'm saying here as "everything you need." So many others have a much deeper and complete understanding of other factors that come into play, such as implied odds in NL games, reverse odds, anti-outs and blockers, that I won't even try to go into all of that here. I just wanted to give you a general idea on where you could get started in "learning the math". So hit that Strategy Page and get to reading. Every hour you invest in CAREFUL study of these concepts will immensely improve your game, guaranteed.
Hope that helps,