What is the probability of getting a sum of 4 when the two number cubes are rolled?

There are 3 combinations - (1, 3), (2, 2), (3, 1) - that will result in a sum of four. Using fair d6 dice, there are 36 possible combinations - 6 on each die, 6 x 6 = 36. Thus there is a 3/36 = 1/12 = 0.0833.. = 8.3% probability.