The proper factors of 64 are 2, 4, 8, 16 and 32. For proper factors of a number exclude 1 and the number itself from the list of factors.
Only 2.
The proper factors of 100 are 2, 4, 5, 10, 20, 25 and 50.
The only proper factor of four is two.
2, 4, 8
2 and 4
1, 2, 4, 5, 8, 10, 20, 40. Technically, that's correct, but proper factors are the factors of a number EXCEPT the number itself. So, the PROPER FACTORS of 40 would be 1, 2, 4, 5, 8, 10, and 20.
Nine proper factors: 1 2 4 5 10 20 25 50 100.
2, 4, 257, 514
2, 4, 23, 46
2, 4, 19, 38
1,2, 4, 8, 16