Binary: This Hindu unit has two possible values: 0 and 1. Modern computer programs are based on binary code. Decimal: The Chinese and the Egyptians were the first to use decimals, which are tenths. The metric system is based on decimal units. The decimal system of writing numbers was introduced into Europe in the 1300s and is now widely used. Duodecimal: The Romans used units of 12. Today we have 12 inches in a foot, 12 months in a year, 12 in a dozen. Sexagesimal: The Babylonians used units of 60. Time is measured in 60s: 60 seconds in a minute, 60 minutes in an hour.
