2
120 combinations using each digit once per combination. There are 625 combinations if you can repeat the digits.
90000
ten factorial = 10! = 3,628,800
If you want 4-digit numbers, there are 24 of them.
a lot
2
210
5040 numbers can be made.
You can make 4*3*2/2 = 12 numbers.
321 312 213 231 123 132 6 3 digit numbers.
If you can repeat a digit, there are 27. If you can't repeat a digit, there are only 6.
-- 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.
120 5-digit numbers can be made with the numbers 12345.
It is: 9C7 = 36
66
10,000