SI derived unit Until 1995, the SI classified the radian and the steradian as "supplementary units", but this designation was abandoned and the units were grouped as derived units. SI derived unit SI derived units are units of measurement derived from the seven base units specified by the International System of Units (SI). They are either dimensionless or can be expressed as a product of one or more of the base units, possibly scaled by an appropriate power of exponentiation. The SI has special names for 22 of these derived units (for example, hertz, the SI unit of measurement of frequency), but the
Per unit tax Per unit tax A per unit tax, or specific tax, is a tax that is defined as a fixed amount for each unit of a good or service sold, such as cents per kilogram. It is thus proportional to the particular quantity of a product sold, regardless of its price. Excise taxes, for instance, fall into this tax category. By contrast, an ad valorem tax is a charge based on a fixed percentage of the product value. Per unit taxes have administrative advantages when it is easy to measure quantities of the product or service being sold. Any tax will