🎯 Permutation & Combination Calculator

Permutations vs Combinations

Permutations count the number of ways to arrange r items from n items where order matters: nPr = n! / (n−r)!. Combinations count selections where order does not matter: nCr = n! / (r! × (n−r)!).

When to Use Each

Use permutations when the order of selection matters (e.g., rankings, passwords, seating arrangements). Use combinations when order does not matter (e.g., lottery numbers, committee selection, card hands). nPr is always greater than or equal to nCr for the same n and r.