What is the probability of rolling a 3 on a 6-sided number cube and then NOT rolling a 3 on a 6-sided number cube? 36

Do determine the probability of two events occurring in sequence, multiply the probability of each event against the other.

There's a 1 in 6 chance of rolling a 3 on a 6-sided number cube; there's a 5 in 6 chance of rolling not-a-3 on a 6-sided number cube; thus, the chance of rolling a 3 that is immediately followed by a not-3 is:

(1/6) times (5/6) = (5/36)