Permutation Calculator

Comprehensive Guide

A permutation calculator counts ordered selections. The notation nPr tells you how many ways you can choose and arrange r items from a set of n items. That is different from combinations, where order does not matter.

This matters in probability, scheduling, and arrangement problems. If the order of selected items changes the outcome, you want permutations. If order does not matter, combinations are the better tool.

Real-World Examples

Choosing 3 leaders from 10 people produces a larger permutation count than combination count because different orders are treated as different results. That is why nPr is the correct model for ranking and seating problems.

The calculator is useful whenever you need a quick check on how large a search space is. The number grows fast, so even small input changes can make the total jump a lot.

Reference Table

Frequently Asked Questions