About combinations (nCr)
This calculator works out nCr — the number of ways to choose r items from a set of n when the order does not matter. Enter n and r and it returns the combination count using nCr = n! / (r! × (n − r)!). It runs in your browser.
How Combinations works
How to use it
- Enter n (total items) and r (how many to choose).
- Read the number of combinations.
How it works
A combination counts selections where order is irrelevant — choosing A then B is the same as B then A. The tool computes nCr efficiently to avoid overflow for large factorials.
Common uses
- Count lottery combinations
- Work out poker hand counts
- Solve probability problems
- Count committee selections
- Help with statistics homework
- Calculate binomial coefficients
- Plan combinations of options
- Learn combinatorics
Frequently asked questions
What is nCr?
The number of ways to choose r items from n, ignoring order.
What is the formula?
nCr = n! / (r! × (n − r)!).
How is it different from permutations?
Combinations ignore order; permutations count order.
What if r is greater than n?
That is invalid — r cannot exceed n.
Is my input uploaded?
No — it calculates in your browser.
Can it handle big numbers?
Yes — large results are shown clearly.
Is it free?
Yes — completely free with no sign-up.