All permutations and combinations of any six numbers from 0 to 9

All permutations and combinations of any six numbers from 0 to 9

In fact, it is a simple multiplication principle. The first bit can only choose 9 numbers, and then each bit can choose 10 numbers
So 9 * 10 * 10 * 10 * 10 * 10 = 900000
If the selected six numbers cannot be repeated
9 * 9 * 8 * 7 * 6 * 5