How it works
n! ÷ [r!(n−r)!]; order does not matter
Input definitions
- Number of items n (0–170)
- Enter the value in the labeled unit.
- Selected items r
- Enter the value in the labeled unit.
A worked example
- Number of items n (0–170)
- 5
- Selected items r
- 2
10
Assumptions & limits
Uses the stated input units. Results are rounded for display; keep additional precision for subsequent calculations.
Sources & review
Maintained by AnsRio. Methods and examples use automated checks; this does not imply independent professional certification.
Method updated 2026-10-17. Content checked against the stated method and examples. Our verification approach.
Common questions
Why can statistical results differ between tools?
Denominator, interpolation and boundary conventions can differ. Use the method and assumptions on this page to compare the same definition; displayed decimals may also be rounded.
How does the Combinations tool work?
n! ÷ [r!(n−r)!]; order does not matter.
What are the assumptions and limits of Combinations?
Uses the stated input units. Results are rounded for display; keep additional precision for subsequent calculations.