EDIT Mathematics The superscript two is an exponent which indicates how many times a number gets multiplied by itself (in this case: two times). A two-times multiplication is also called a square or square number. It can also be referred to as a power: a number with an exponent of two is raised to the second power.

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EDIT Measure If the superscript two is used with a measure of length (such as meter, m) it becomes a surface unit (m²).

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EDIT Indonesian Plural The Indonesian language (Bahasa Indonesia) doesn't have a plural. A plural or increase is often expressed by dublication. In informal correspondence or private notes, this kind of plural is often written with a "²".

Examples:
person = orang
persons = orang-orang (official notation)
persons = orang² (informal notation)

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