<Tr> <Th> feet </Th> <Td> 0.003 2808 ft </Td> </Tr> <P> The millimetre (International spelling as used by the International Bureau of Weights and Measures; SI unit symbol mm) or millimeter (American spelling) is a unit of length in the metric system, equal to one thousandth of a metre, which is the SI base unit of length . Therefore, there are one thousand millimetres in a metre . There are ten millimetres in a centimetre . </P> <P> One millimetre is equal to 7003100000000000000 ♠ 1000 micrometres or 7006100000000000000 ♠ 1000000 nanometres . A millimetre is equal to exactly ​ ⁄ (approximately 0.039370) of an inch . </P> <P> Since 1983, the metre has been defined as "the length of the path travelled by light in vacuum during a time interval of 1 / 7008299792458000000 ♠ 299 792 458 of a second". A millimetre, 1 / 1000 of a metre, is therefore the distance travelled by light in 1 / 7011299792458000000 ♠ 299 792 458 000 of a second . </P>

1 km is equal to how many millimetre