Density, mass of a unit volume of a material substance. The formula for density is d = M/V, where d is density, M is mass, and V is volume. Density is commonly expressed in units of grams per cubic centimetre. ... For example, the density of air is 1.2 kilograms per cubic metre.
The length unit of decimeter is 100 times larger than a millimeter. The relationship between length units is 1 meter = 10 decimeter = 100 centimeter = 1000 millimeter.