More generally properties can be combined to give new properties, which may be called derived or composite properties. For example, the base quantities mass and volume can be combined to give the derived quantity density. These composite properties can sometimes also be classified as intensive or extensive. Suppose a composite property formula_1 is a function of a set of intensive properties formula_2 and a set of extensive properties formula_3, which can be shown as formula_4. If the size of the system is changed by some scaling factor, formula_5, only the extensive properties will change, since intensive properties are independent of the size of the system. The scaled system, then, can be represented as formula_6.