On a cube there are 6 sides. There are three odd numbers and one 4, so the probability of rolling these numbers is 4/6 which is 2/3. To get the probability of it from two rolls, we multiply it by itself once because it is being rolled once more. 2/3 x 2/3 is 4/9, so the probability of rolling an odd number or four in two roles is 4/9.
