Yes. 17 is a proper factor of 34.
The answer is 13.
2
4
A proper 2-digit number (which must be smaller than 100) cannot be twice a 10-digit number (which must be larger than 999,999,999).
11
Even.
That would be 75.
1 out of 2
1 out of 2
10, 20, 25, 50
65
2 is a prime number and has no factors other than 1 and itself.