Enter a number n and number r into the choose calculator. The combination calculator will return the value of n choose r.

Choose Formula

The following formula is used to calculate n choose r given two integers n and r.


  • Where n is an integer
  • r is an integer
  • and ! is factorial

Choose Definition

Choose is a term used in math to describe the operation of taking the combination of two numbers.

How to calculate choose?

How to calculate a combination

  1. First, determine the number of options to choose from

    This will be the number n in the formula above. It will be all the available options to choose from.

  2. Next, determine the number of options you wish to choose

    This will be the number of objects or options you choose out of the total number of options.

  3. Calculate the combination

    Calculate n choose r using the formula above.


What is n choose r?

N choose r is another way of saying the mathematical operation of a combination.

What is a combination?

In mathematical terms, a combination is as it sounds, it’s a numerical operation that displays the total number of options to choose from given a set of objects or numbers. The combination will yield all possible combinations of r integers from a set of n integers. For example, let’s say we have a set of numbers 1,2,3. We want to choose all possible combinations of 2 integers. This yields the following: 1,2 / 1,3 / 2,3 = 3 total combinations.