How many 8 digit numbers are there, such that they are divisible by 9 and all of the digits are distinct?
My computer says there are: 181,440 eight-digit numbers between 10,236,789 and 98,763,210 that are divisible by 9. Somebody will confirm this using combinatorics such as 9! / 2! or 10 nPr 8 / 10 or 9 nPr 8 / 2!...etc.