Probability Calculator
Single events, combined events, conditional probability, combinations & permutations
Mode
Probability of Event A (%)
%
Result
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—
Odds For—
Odds Against—
Probability Rules
- Addition rule: P(A∪B) = P(A) + P(B) − P(A∩B)
- Multiplication (independent): P(A∩B) = P(A) × P(B)
- Conditional probability: P(A|B) = P(A∩B) / P(B)
- Complement: P(not A) = 1 − P(A)
- Combinations: C(n,r) = n! / (r! × (n−r)!) — order doesn't matter
- Permutations: P(n,r) = n! / (n−r)! — order matters
lightbulb Lottery Example
Pick 6 from 49 numbers (nCr):
1n=49, r=6
2C(49,6) = 13,983,816 combinations
✓ P(jackpot) = 1 in ~14 million