Per cent mille

Per cent mille, often written as "permille" (‰), is a unit of measurement that represents parts per thousand. It is similar to the concept of percentage, where percentage means parts per hundred, but permille is scaled to a base of one thousand. In mathematical terms, 1 permille is equal to 1/1000 or 0.1%. It is often used in contexts such as measuring concentrations (e.g., in chemistry) or in statistics.