Permutation and Combination Calculator
Enter the total number of items n and the selection size r to calculate both results locally.
A QUICK WALKTHROUGH
How to use this tool
- Enter integer values for n and r.
- Calculate the permutation and combination counts.
- Compare the ordered and unordered results.
What the results count
Permutation P(n,r)=n!/(n−r)! counts selections where order matters. Combination C(n,r)=n!/[r!(n−r)!] counts selections where order does not matter.
Input limits
Use integers satisfying 0 ≤ r ≤ n ≤ 100. Calculation runs in this browser.
GOOD TO KNOW
Common questions
When should I use a permutation?
Use P(n,r) when changing the order creates a different result, such as assigning first and second place.
When should I use a combination?
Use C(n,r) when only which items are selected matters, not their order.