Combination & Permutation Calculator
Calculate the number of combinations (nCr) and permutations (nPr) for choosing r items from n.
Combinations C(n,r)
120
Permutations P(n,r)
720
How it works
Permutations count ordered arrangements: P(n,r) = n!/(n−r)!. Combinations count unordered selections: C(n,r) = P(n,r)/r!.
What's the difference between the two?
Permutations care about order (ABC ≠ BCA); combinations don't (ABC = BCA counts once).