In mathematics, the concept zero is used in two ways: as a number and as a value of a variable. The positional system of number notation, developed first by the Babylonians with the base 60, and later by the Hindus and the Chinese with the base 10, required for greater clarity a special marker of the empty, nonoccupied position. As such, the symbol for zero was introduced by the Babylonians (about 500 B.C.), and a millennium later it appeared in the Indian system of notation, which came to the West through the Arabs as the arabic number system.