<P> The value, or number, zero is not the same as the digit zero, used in numeral systems using positional notation . Successive positions of digits have higher weights, so inside a numeral the digit zero is used to skip a position and give appropriate weights to the preceding and following digits . A zero digit is not always necessary in a positional number system, for example, in the number 02 . In some instances, a leading zero may be used to distinguish a number . </P> <P> The number 0 is the smallest non-negative integer . The natural number following 0 is 1 and no natural number precedes 0 . The number 0 may or may not be considered a natural number, but it is a whole number and hence a rational number and a real number (as well as an algebraic number and a complex number). </P> <P> The number 0 is neither positive nor negative and is usually displayed as the central number in a number line . It is neither a prime number nor a composite number . It cannot be prime because it has an infinite number of factors, and cannot be composite because it cannot be expressed as a product of prime numbers (0 must always be one of the factors). Zero is, however, even (as well as being a multiple of any other integer, rational, or real number). </P> <P> The following are some basic (elementary) rules for dealing with the number 0 . These rules apply for any real or complex number x, unless otherwise stated . </P>

Who discovered zero and where was it used first