Probability, also known as probability, chance rate or probability and possibility, is the basic concept of mathematical probability theory, a real number between 0 and 1, and a measure of the possibility of random events.

There are many formulas for probability. I don't know which one you want:

1.P (φ) = 0。 Characteristic 2 (limited additivity). When n events A 1, …, An are incompatible with each other: p (a1∧ ... ∪ an) = p (a1). B satisfies that a is included in b: P(BnA)=P(B)-P(A), and p (a) ≤ p (b). Property 5. For any event a, p (a) ≤ 1. Real estate 6. For any two events a and b, p(B-A)= 1