Combination and Permutation Calculator

This calculator works out how many ways you can choose r items from a set of n, both when order matters and when it does not. Enter the total number of objects and how many you are selecting, and it returns the permutation count and the combination count side by side. The difference is the point: permutations treat ABC and CBA as two outcomes, combinations treat them as one. It saves working through factorials by hand when the numbers get large.