Define one metre, the S.I. unit of length. And state it's one multiple and one submultiple.

One metre :

1. One metre is defined as the distance travelled by light in a vacuum during a time interval of $\frac{1}{299792458}$of a second.
2. The S.I unit of length is metre.
3. Multiple of a metre is Kilometre (km), where 1 km = 1000 m.
4. Submultiple of metre is centimetre (cm), where 1 cm = 10 ^-2 m.