27 three digit numbers from the digits 3, 5, 7 including repetitions.
24
It is possible to create a 3-digit number, without repeated digits so the probability is 1.
Five numbers (5, 6, 7, 8, 9) can be selected for each of the 5 digits. So, there are 5*5*5*5*5 or 55 or 3125 five digit numbers.
The largest 10-digit number with no digit repeated is 9876543210 !
24
500
24
5040 different 4 digit numbers can be formed with the digits 123456789. This is assuming that no digits are repeated with each combination.
1 set
It is 120 if the digits cannot be repeated.
There are 5! = 120 such numbers.
3x3x3=27
4*3*2*1 = 24
48 of them if digits may not be repeated. 100 if they can.
6*6*3 = 108 numbers.
36
6*5*4*3*2*1=720 possible numbers