Flip coins, roll dice, draw cards. Build compound events and watch experimental probability converge to theory as you run thousands of simulations.
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Build any compound event: choose an event type, an outcome, and optionally combine two events with AND, OR, or NOT. The theoretical probability updates instantly. Then run thousands of simulations to verify.
Event Builder
Quick Presets
Theoretical Probability
Theoretical Probability
0.500 (50.0%)
Rule Applied
Basic Probability
Out of 2 possible outcomes, 1 match your event.
Simulation
A die is rolled once. Circle A = even result, Circle B = result greater than 3. Toggle AND / OR / NOT A to see which regions are highlighted, and click regions to explore their counts and probabilities.
Highlighted: A AND B
2/6 outcomes, P = 0.333
Click a region to explore
Multiplication Rule
For independent events A and B: P(A AND B) = P(A) × P(B). Each event's outcome does not affect the other.
Addition Rule
P(A OR B) = P(A) + P(B) − P(A AND B). Subtract the overlap to avoid counting shared outcomes twice.
Complement Rule
P(NOT A) = 1 − P(A). All probabilities sum to 1, so the complement fills the rest of the sample space.