Arithmetic & Number Theory
Combinations (nCr)
Unordered selections of r from n.
Formula
Formula
C(n,r) = n!r!(n−r)!
Variables
| Symbol | Definition | Type & range | Units | Role |
|---|---|---|---|---|
| n | total items | integer (ℤ) | — | input |
| r | chosen items | integer (ℤ) | — | input |
Try it yourself
Interactive calculator
Worked examples
Example 1
Givenn = 10, r = 3
Result120
Example 2
Givenn = 49, r = 6
Result13983816