Which of the following conversion factors would you use to change 18 meters to kilometers?

A. 1000 m/1 km

B. 1 km/1000 m

C. 100 m/1 km

D. 1 km/100 m

In converting a number with the unit of meter into kilometer we must use the conversion factor 1 km per 1000 meters. This is because in 1 kilometer there are 1000 meters and then the unit to be converted is already in meter so we need to divide it for us to convert.