What is 289 divisible by?

Answer 1

No, 288 is, but 289 is not.

For a number "x" to be divisible by 4, "x" must be even, and "x/2" must be even as well.

289 is not even. ■

To check whether or not the number is divisible by 4 it is enough to check (as above) that the last two digits of the number are divisible by 4. In this case, it would be to check that 89 is divisible by 4.

Answer 2

1, 17, 289.

Answer 3

1, 17, 289