Question 174518
The highest order digit must be 1-9 (it can't be 0)
so, there are {{{9}}} choices
The next digit can be 0-9, minus the choice I just made
So  far I have
{{{9*9 = 81}}} choices
There are {{{8}}} choices for the 3rd digit, 
{{{7}}} for the 4th
{{{6}}} for the 5th
{{{5}}} for the 6th
{{{4}}} for the 7th
{{{3}}} for the 8th
{{{2}}} for the 9th
The number of possible 9 digit numbers with different digits is is
{{{9*9*8*7*6*5*4*3*2 = 3265920}}} answer