a reference point from which all other measurements are made is called a(n)
Measurement The metric system features a single base unit for many physical quantities. Other quantities are derived from the standard SI units. Multiples and fractions are expressed as powers of 10 of each unit. When smaller or larger units are more convenient for given use, metric prefixes can be added to the base unit to denote its multiple by a power of ten: a thousandth (10âˆ’3) of a metre is a millimetre, while a thousand (103) metres is a kilometre. Unit conversions are thus always simple, so that convenient magnitudes for measurements are achieved by simply moving the decimal place: 1.234 metres is 1234 millimetres or 0.001234 kilometres. The use of fractions, such as 2/5 of a metre, is not prohibited, but uncommon. There is no profusion of different units with different conversion factors as in the Imperial system which uses, for example, inches, feet, yards, fathoms, and rods for length.