##150 mm div 10 div 10 = 150/(10xx10) = 1.5dm##

Although decimeters exist, they are seldom used in this form.
We prefer to use metres, centimetres and millimetres.

We would say 20 cm rather than 2 dm, although the length is the same.

The conversion between the units of length is by a factor of 10 each time.

Multiply by 10 to covert to the next smaller unit or divide by 10 to change to the next bigger one.

##150 mm div 10 div 10 = 150/(10xx10) = 1.5dm##

However decimetres are important because they offer another link between length and capacity.

A cube that is

##10cmxx 10cmxx 10 cm## is the same as ##1 dm^3##

It holds exactly 1 litre.

So we have:

##1 cm^3 = 1cc = 1ml##

##1 dm^3 = 1 litre##

##1 m^3 = 1 Kl ##

The conversion factor between these is 1000.