Zero, in arithmetic, is the name of the digit 0, sometimes called nought or, in the past, a cypher. It is used to indicate the absence of quantity. A zero is needed in a positional nu meral system, such as the familiar system commonly used by most people today. In a positional system, the position, or place, of a digit determines the digit's value. Thus, in the numeral 246, the digit 2 stands for two hundred, the digit 4 stands for four tens (or forty), and the digit 6 stands for six units, or ones. The numeral represents the number 246. In order to write the number 206, a symbol is needed to show that there are no tens. The digit 0 serves this purpose. Zero added to or subtracted from a number gives the original number. A number multiplied by zero gives zero. Division by zero is undefinable.

On most scales, zero marks the starting point or the neutral position. Positive numbers are placed to the right or above zero, and negat ive numbers are placed to the left or below zero. But on some scales, zero is set arbitrarily. For example, on a Celsius thermometer, zero is set at the temperature at which water normally freezes. This is said as 0 degrees Celsius.

The Maya Indians of Central America are believed to have invented the concept of the zero before the AD 300's. The Hindus developed the concept independently several hundred years later. The idea spread from India and was adopted in Europe during the late 1400's. The word zero probably came from ziphirum, a Latinized form of the Arabic word sifr.Sifr is a translation of the Hindu word sunya (void or empty).