We call it The Slot Method.  Using this method, when asked to find a probability of a compound event A, we will find the total number of outcomes, n(S), and the total number of successful outcomes n(A) and use slots for each of the number of events (either independent or dependent) that make up the compound event.

phrasal verb\n\n : to find a place for (someone or something) in a schedule, plan, etc. I can slot you in at 2 p.m.