Math & Statistics
Combination Calculator
Calculate the number of unordered selections of r items from n items.
TOOL 47
Enter your values
Use the fields below to calculate your result.
Result
10
n5
r3
Formula: C(n,r) = n!/[r!(n − r)!].
How to use this calculator
What to enter
Enter or select the following as requested: n (total items); r (selected items). Follow the units, valid ranges, examples, and options displayed beside each field.
What the result means
The probability or counting result follows the model and assumptions selected in the form. Confirm whether events are independent, whether order matters, and which distribution or probability definition is being used.
When to use it
Use this to calculate a probability or count possible outcomes under a defined model. Treat the result as conditional on the assumptions and inputs.