What is the Combination Calculator?
Count unordered selections (combinations) of r items from n. From percentages and fractions to logarithms and quadratic equations, these math calculators show exact results — using arbitrary-precision integers wherever whole-number answers can get very large.
How to use the Combination Calculator
- Enter your total items, your chosen.
- Results update automatically as you type; you can also press Calculate.
- Read the output: combinations ncr, odds of one specific combination.
- Use the 📊 chart to see the result visually, then copy or share it.
Formula and method
Worked example
With total items = 49, chosen = 6, the Combination Calculator returns combinations ncr: 13,983,816; odds of one specific combination: 1 in 13,983,816.
Tips for better results
- Use the formula section on each page to check your homework method, not just the answer.
- For very large factorials, combinations and base conversions we use exact big-integer math.
- Floating-point results are rounded to 12 significant digits to remove binary noise.
Frequently asked questions
What does the Combination Calculator do?
Count unordered selections (combinations) of r items from n.
How is it calculated?
The Combination Calculator uses this method: nCr = n! ÷ (r! (n − r)!).
Can you show an example?
With total items = 49, chosen = 6, the Combination Calculator returns combinations ncr: 13,983,816; odds of one specific combination: 1 in 13,983,816.
Is the Combination Calculator accurate?
Yes. It uses standard formulas and exact constants, and the results are verified by our automated test suite. Values are displayed to up to 12 significant digits.
Is this tool free and private?
Yes — the Combination Calculator is completely free with no sign-up, and it runs entirely in your browser, so the values you enter are never uploaded to our servers.
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