How many combinations are possible with 3 numbers?

I'm assuming they're three unique numbers. Thus, the first can be any of three, the second either of the remaining two, and the last is the last one left. Thus:

combinations = 3 * 2 * 1 = 6

Or, more generally, the combinations of n numbers in such a problem is n factorial, denoted as "n!", which is every number from 1 to that number multiplied together.