There's also a connection to probability: if you want the probability of A and B and C happening and they're independent, it's P(A) * P(B) * P(C). If you want

There's also a connection to probability: if you want the probability of A and B and C happening and they're independent, it's P(A) * P(B) * P(C). If you want the probability of A or B or C happening and they're mutually exclusive, it's P(A) + P(B) + P(C). Similar analogue for set theory, as another commenter pointed out.