There are 10 possible digits (0 through 9). However, for a 3-digit number, the first digit cannot be 0, so it must be one of the digits from 1 to 9. Therefore, there are 9 valid choices for the first digit. If using only one digit to form the entire number, the only valid 3-digit numbers would be 111, 222, ..., 999, resulting in a total of 9 three-digit numbers.
210
5040 numbers can be made.
321 312 213 231 123 132 6 3 digit numbers.
-- 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.
24
a lot
2
210
5040 numbers can be made.
9
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.
20 of them, if repetition is not allowed.
15