Decimal System, a method of expressing weights and measures in units that are in the ratios 1000, 100, 10, 1, 1/10, and 1/1000, to each other. In the French or metric system we have, for example, the unit of mass, one gramme. From this are derived by repeated tenth-multiplication the decagramme, hectogramme, and kilogramme; and by repeated tenth-division the decigmmme, centigramme, and milligramme. Throughout the system the Greek prefixes denote multiples of the unit, and the Latin prefixes denote submnltiples thereof. Thus a millimetre is the thousandth part of a metre, the hectometre is a hundred metres, and a decigramme is the tenth of a gramme.