Combination (Kumiawase)

Kumiawase (組合わせ), or combination, refers to a way of choosing r items from n different items without regard to order. Each such selection is called a combination, and in mathematics the number of them is written nCr. It is calculated with the formula nCr = n! / (r! (n − r)!), where n! (n factorial) means the product of all integers from n down to 1. Combinations are widely used when forming groups from a set of options. In the world of sake, different sake rice varieties and brewing methods are also combined when blending, which contributes to a greater diversity of flavor.