The units were interrelated. Units of one measure, such as length, increased by powers of ten (millimeters, centimeters, decimeters, meters). A liter was the volume of a cube 10 centimeters on a side.

Kilometres would be a far more appropriate unit of length. Work out what 3 m is in centimetres. To convert a larger unit to a smaller unit (eg m to cm) first check the number of small units needed ...

the same symbol is also used for a unit of length (the first Bohr radius) for a unit of electric moment and, in quantum field theory, for a quite different energy. To compound the confusion ...

―Units of Length― Barky realizes that the measurement can be made by counting how many 1-centimeter items are needed, and the customer's foot is measured successfully. Transcript ...