39
3x13 39x1
Assuming without repeats: 40C5 = 40!/(40-5)!5! = 40x39x38x37x36x35x34x...x2x1/(35x34x...x2x1)x(5x4x3x2x1) = (5x4x2)x(3x13)x38x37x36/5x4x3x2x1 = 13x38x37x36 = 658008
39
1x52, 2x26, 3x13
3x13 39x1
The product of 13 x 3 is 39
3x13=39
3x13=39
I'm sure it's composite, 3x13=39
3 is a prime number. 13 is a prime number. 3 x 13 cannot be prime.
33 (3x11) 39 (3x13) 51 (3x17)
3 because they are all in multiples of 3 3x4 and 3x13
4x10 is 40 which is as close as you can get.If you want to get close but not 40 itself, then 3x13=39 which is closer then 4x9=36
17