Kansberekening calculator
The detailed guide below is currently available in English.
The AND and OR rules
Two events combine under one key question: must both happen, or does either one count? For independent events, AND multiplies — rolling a six and flipping heads is (1/6) × (1/2) = 1/12, because the paths branch independently. OR adds but must subtract the overlap so it is not counted twice: P(A or B) = P(A) + P(B) − P(A and B). Equivalently, the four paths "A only", "B only", "both", and "neither" are mutually exclusive and sum to exactly 100%, which this calculator lists so you can trace every branch of the tree.
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What makes two events independent?
One occurring does not change the other’s probability. Separate dice, coins, or different people drawn one at a time with replacement are independent; cards drawn without replacement are not, since each draw shrinks the deck.
How is probability different from odds?
Probability compares favorable outcomes to all outcomes — 1/6 — while odds compare favorable to unfavorable: 1 to 5. The single-event tab shows both, plus the complement.