Keno

[brassnuts]

I know playing any keno game is a horrible bet, and I would never play it. However, at lunch today, a friend placed a couple bets... actually won $60 bucks on a 2-spot. Anyways, I thought at first that odds would be easy to figure out, but then after a couple seconds of thinking about it, I realized I didn't know how to properly figure the odds in this lottery type game.
I get confused because I presume that the odds would change depending on when you assume you hit your picks. Am I correct that the odds do change in this manner? Say you're playing a 6-spot, how would you calculate the odds?

[Mano]

If you want to find out the probability of n selections coming up out of the 20 selected items, you can do the following:

There are C(80 - n, 20 - n) different 20 number combinations containing your n numbers on an 80 number board. There are C(80,20) different ways to choose 20 numbers from an 80 number board, so the probability of selecting n numbers correctly is C(80 - n,20 - n)/C(80,20)