The international standard unit of length is meter, and centimeter is one hundredth of meter, that is, 1 meter = 100 cm. Therefore,1km =1000m =1000x100cm =100000cm. In other words, 1 km is equal to one million centimeters. This is a basic mathematical concept.

In addition, in real life, we often need to convert length units. For example, when buying clothes, the clerk will ask your size, which is usually expressed in centimeters or inches. So it is very useful to understand the conversion relationship between different length units.