We know that the standard unit of length is ‘Meter’ which is written in short as ‘m’.
Mostly we use Kilometer (km), Meter (m) and Centimeter (cm) as the units of length.
If you look at the ruler you can find that one centimeter is divided into 10 equal parts which are marked by smaller lines. Each line represents 1 millimeter. So, 10 millimeters is equal to 1 cm. 10 mm = 1 cm.
To convert kilometer into meters we multiply by 1000 and meters into kilometer we divide by 1000.