If repetition is allowed . . . . . 343
If repetition is not allowed . . . . . 210
100,000
12
24
There are 504 such numbers.
6
840
9999
100,000
512
12
24
There are 504 such numbers.
There are 60480 numbers.
6
823543
There are 5! = 120 such numbers.
The number 1234567890 can create about 39 of 40 4 digit numbers.