Statistics
Combination
What is the Combination?
Unordered selections of r from n
This formula is widely used in statistics applications. Understanding when and how to apply it helps you interpret calculator results correctly and catch input errors before they propagate.
Formula
nCr = n! / (r!(n-r)!)
Substitute known values into the formula above. Ensure all variables use consistent units before calculating.
Worked Example
10C2 = 45
Use the linked calculator below to try your own values and see step-by-step working.
When to Use This Formula
Apply the Combination when you need to unordered selections of r from n. It is a standard reference in statistics coursework, professional practice, and our linked calculators.
Tips & Common Mistakes
- Confirm whether you need sample or population formulas.
- Report spread measures alongside averages.
- Always verify critical results independently for engineering, medical, or legal applications.
Related Calculators
Further Reading
Browse the Formula Library for related formulas, or read educational articles on our Blog.