try dividing..
39 divided by 1 equals 39
39 divided by 2 equals 19.5
39 divided by 3 equals 13
39 divided by 4 equals 9.75
39 divided by 5 equals 7.8
39 divided by 6 equals 6.5
39 divided by 7 equals 5.57
39 divided by 8 equals 4.8
39 divided by 9 equals 4.33
39 divided by 10 equals 3.9
So the only whole number would be 13.
So 13 times 3 equals 30
