How Many Number combinations are there in 0-9?

Answer 1

9

Answer 2

In all there are 210 - 1 = 1023 combinations.

Of these,

1 has all 10 digits

10 have 1 or 9 digits

45 have 2 or 8 digits

120 have 3 or 7 digits

210 have 4 or 6 digits

252 have 5 digits.

In a combination, the order of digits does not matter.