1000
210 of them.
99999
192 ways
500
744 digits.
6*5*4*3*2*1=720
36
10,000
If the digits can be used more than once, then 900. If not, then 648.
99999
210 of them.
192 ways
There are 7,290 different 4-digit numbers that can be formed from the digits 1-9 without repetition.
24
500
744 digits.
1 set