Given digit in the number = 9

1st place can be filled = 9 ways = 9 (from 1-9 any number can be placed at first position)

2nd place can be filled = 9 ways (from 0-9 any number can be placed except the number which is placed at the first position)

3rd place can be filled = 8 ways

4th place can be filled = 7 ways

5th place can be filled = 6 ways

6th place can be filled = 5 ways

7th place can be filled = 4 ways

8th place can be filled = 3 ways

9th place can be filled = 2 ways

So total number of ways = 9*9*8*7*6*5*4*3*2

                                     = 9*9!