Math
Combination Calculator
Find how many ways r items can be chosen from n items when order does not matter.
The result is the number of different groups of r items that can be chosen from n items when order does not matter, so it counts each distinct selection only once.
Formula
Combination C(n, r) = n! ÷ (r! × (n − r)!), because order does not matter when only choosing items.
How it works
Enter n and r with r no larger than n. The calculator divides by the factorials of both parts. For example, C(10, 3) = 120.
FAQs
What does the Combination do?
It takes the values you enter and works out the combination for you, showing the result straight away.
What should I enter?
Enter ordinary numbers in the boxes above. If a value does not make sense for this calculation, the page will ask you to check it instead of showing a wrong answer.
Can I use the result for homework or everyday math?
Yes. It is a general-purpose math helper; for exam or professional work, still check the steps against your own working.
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