a lot
2
210
9
You can make 4*3*2/2 = 12 numbers.
5040 numbers can be made.
-- If the same digit may be repeated, then 64 can be made. -- If the same digit may not be repeated, then 24 can be made.
321 312 213 231 123 132 6 3 digit numbers.
120 5-digit numbers can be made with the numbers 12345.
If you can repeat a digit, there are 27. If you can't repeat a digit, there are only 6.
20 of them, if repetition is not allowed.
15
10,000