What is this calculator?
Count ordered selections and unordered combinations.
What can you use it for?
Use it when solving an exercise, checking a result, or working with the particular quantities shown in this form. Count ordered selections and unordered combinations.
How to use it
- Enter total items n.
- Enter selected items r.
- Select Calculate (or Generate for random tools).
- Read the answer and any additional results below the form. Check the units and the limits of the method.
Formula and method
nCr = n! ÷ [r!(n−r)!]
Permutation counts ordered selections; combination counts selections where order does not matter.
Worked example
Total items n: 10, Selected items r: 3. The result is 120 (combinations ncr).
Assumptions and limits
Inputs and outputs must stay within the supported finite number range. Displayed decimal answers may be rounded.
Frequently asked questions
What inputs does the Permutation and Combination Calculator need?
Use total items n, selected items r. Read the answer and any additional results below the form. Check the units and the limits of the method.
What assumptions apply to the Permutation and Combination Calculator?
Inputs and outputs must stay within the supported finite number range. Displayed decimal answers may be rounded.