Adding and subtractingSI prefixes creates multiples and submultiples; however, as the unit isexponentiated, thequantitiesgrow exponentially by the correspondingpower of 10. For example, 1kilometre is 103 (onethousand) times the length of 1 metre, but 1 square kilometre is (103)2 (106, onemillion) times the area of 1 square metre, and 1 cubic kilometre is (103)3 (109, onebillion) cubic metres.
Unicode has several characters used to represent metric area units, but these are for compatibility with East Asian character encodings and arenot meant to be used in new documents.[2]
U+33A1㎡SQUARE M SQUARED
U+33A2㎢SQUARE KM SQUARED
U+3378㍸SQUARE DM SQUARED
U+33A0㎠SQUARE CM SQUARED
U+339F㎟SQUARE MM SQUARED
Instead, theUnicode superscriptU+00B2²SUPERSCRIPT TWO can be used, as in m².
