Any system of naming or representing numbers, as the decimal system or the binary system. Also called numeral system. Method of writing numerals to represent numbers. The use of zero as a placeholder was the greatest advance in number systems. The most common system is the decimal system, in which 10 symbols (the Hindu-Arabic numerals) denote multiples of powers of 10 by their position relative to the decimal point. Computers have brought greater awareness of the binary number system, in which two symbols, 0 and 1, represent multiples of powers of 2