If you roll a fair six-sided die in a four-sided die what is the probability that at least one side shows a 4

There is a 3/8 chance of showing at least on four.

To find this probability, we must first add together the chance of rolling a four on either die.

1/6 + 1/4 = 5/12

Then, we must subtract away the probability of getting a 4 on both die, because we don't want to count that twice only once.

5/12 - 1/24 = 3/8