An arithmetic operation commonly used in a wide range of statistical calculations. In writing the binomial coefficient is denoted using two vertically aligned numbers encapsulated by round brackets. In speech, the term "choose" is typically used as the operator. I.e. "a choose b" means the binomial coefficient with the operands a and b, just like "a minus b" means subtraction with the operands a and b. The binomial coefficient is used to calculate the total number of different ways in which a set of items can be selected from a collection, where the selection order does not matter.

For example there are "four choose two" equals six ways to pick two colours from a palette containing four colours: (red yellow green blue). Namely: (red yellow), (red green), (red blue), (yellow green), (yellow blue) and (green blue).