Probability Calculator
Work out permutations, combinations, and simple probability with clear formulas and instant results.
Permutation Calculator (P(n,r))
P(n,r) = n! / (n-r)!
Number of permutations:
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Combination Calculator (C(n,r))
C(n,r) = n! / (r! * (n-r)!)
Number of combinations:
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Probability Calculator
Probability:
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Probability Calculator Guide
This page combines three common probability tasks in one tool: permutation, combination, and simple favorable-outcome probability. It is useful for exam practice, statistics homework, and quick checks when order matters or does not matter.
Permutations
Use permutations when the order of selected items changes the result.
Combinations
Use combinations when you only care about the selected group, not its order.
Simple Probability
Enter favorable and total outcomes to see both decimal and percentage probability.
Quick Tips
- For permutations and combinations, keep r less than or equal to n.
- Use permutation when arrangement order matters, such as ranking or seat order.
- Use combination when order does not matter, such as choosing a team or committee.
- For basic probability, favorable outcomes cannot exceed total outcomes.
Core Formulas
Permutation
P(n,r) = n! / (n-r)!
Combination
C(n,r) = n! / (r! * (n-r)!)
Probability
P(E) = favorable outcomes / total outcomes