99999
500
180 of them.
There are 5 numbers of 1 digit, 25 numbers of 2 digits, and 75 numbers of 3 digits. This makes 105 numbers in all.
There are 34 = 81 numbers.
99999
5040 different 4 digit numbers can be formed with the digits 123456789. This is assuming that no digits are repeated with each combination.
24
500
840
There are 60480 numbers.
180 of them.
There are 3024 of them.
1 set
There are 5 numbers of 1 digit, 25 numbers of 2 digits, and 75 numbers of 3 digits. This makes 105 numbers in all.
There are 4^6 = 4096 such numbers.
If the digits are all different then 18. Otherwise, 192.