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Leave a space between kilometre (or its symbol km) and the number that immediately precedes it.
SI usage, followed in scientific and technical writing, prescribes that both the number and the unit name be written in full (e.g. fifteen kilometres) or that the numeral be followed by the symbol (e.g. 15 km). However, general usage accepts numerals with spelled-out unit names (e.g. 15 kilometres), to improve comprehension.
When no specific figure is stated, write kilometre in full.
Because the metric (SI) system uses symbols, not abbreviations, the symbol km for kilometre does not contain periods, or an s in the plural form.
The symbol km is always in lower case, even when the rest of the text is in upper case, as in a newspaper headline.
Kilometres per hour is expressed as km/h (not kmh or kph).
Area and volume in the metric system are expressed by means of superscript numerals: not square kilometres but km².
For the sake of clarity, when kilometre is used as a modifier, a hyphen is inserted between the numeral and the unit name.
However, if the symbol km is used, do not put a hyphen between the numeral and the symbol.
K is not an official symbol for kilometres, but races are often described by this letter. Do not leave a space or put a hyphen between the numeral and the symbol K.
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