If you have T9, what are the chances that the flop will give you either a straight or place you one card from having a straight?

I know how to figure odds when just one card is missing (aka, what are the odds of getting a club with 47 cards to go) but i have no idea how to figure the odds when your looking for 2 cards instead of just one.

T9 and the chances of getting a 8 or a J is easy to figure, but what about getting either 8 AND J, or J AND Q, or 8 AND 7, or J AND Q AND K, or J AND Q AND 9, or J AND 9 AND 8, or 8 AND 7 AND 6? (if i even rembered them all)

How do i figure out thoes odds?

Thanks
David