How many combinations of 5 numbers are there in 10 numbers?

Answer 1

If the order of the 5 matters, there are (10 x 9 x 8 x 7 x 6) = 30,240 possibilities.

If the order of the 5 doesn't matter, there are (30,240)/(5 x 4 x 3 x 2) = 252 unique groups of 5.

We assumed that the same number can't repeat within the 5.