find the total numbers of nine digit numbers which have all different digits. Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website! The highest order digit must be 1-9 (it can't be 0)
so, there are choices
The next digit can be 0-9, minus the choice I just made
So far I have choices
There are choices for the 3rd digit, for the 4th for the 5th for the 6th for the 7th for the 8th for the 9th
The number of possible 9 digit numbers with different digits is is answer
