There are no three didgit numbers but there are 63 three digit numbers.
8
30
There are 900 three-digit numbers.
300300300300
There are no three didgit numbers but there are 63 three digit numbers.
8
144
24 if you don't repeat any numbers.24
25=20,21,23
30
A lot
There are only 999 three digit whole numbers.
171
There are 900 three-digit numbers.
300300300300
45