Zero.
3
There are 5760 such numbers.
500
6*6*3 = 108 numbers.
There are 5460 five digit numbers with a digit sum of 22.
5 x 10 x 5 = 250 different numbers, assuming there is no limit to each digits' use.
There are 5760 such numbers.
There are 41 of them.
500
There are 500000 such numbers.
25 of them
None, because you do not have three even digits. None, because you do not have three even digits. None, because you do not have three even digits. None, because you do not have three even digits.
17
With 123 digits you can make 123 one-digit numbers.
6*6*3 = 108 numbers.
There are 5460 five digit numbers with a digit sum of 22.
More than one
The second digit can be 2,4,6, or 8. There are 4 ways of choosing the second digit. The first digit can be chosen from the remaining 8 digits. 8x4 = 32 numbers. Here, it is assumed that the numbers do not repeat