NOBODY KNEW HOW MUCH we needed nothing until we had a number for it. Without zero, negative and imaginary numbers would have no meaning, and it would be impossible to solve quadratic equations, a mainstay of applied math. Without zero to act as a placeholder to distinguish, say, 10 from 100, all but the simplest arithmetic requires an abacus or counting board. “If we didn't have zero, our system of numbers would be incomplete,” says Charles Seife, author of Zero: The Biography of a Dangerous Idea. “It would really break down without zero.”
Zero arrived on the scene in two installments. Around 300 B.C., Babylonians developed a proto-zero—two slanted wedges pressed into clay tablets—that served as a placeholder in their funky sexagesimal, or base 60, number system. By the fifth century, the concept of zero migrated to India and made its symbolic entrance as a dot carved on a wall at the Chaturbhuja Temple in Gwalior. Then, like a pebble dropped into a puddle, the symbol for zero expanded to an “0” and became a number with properties all its own: an even number that is the average of −1 and 1. In 628 mathematician Brahmagupta pontificated on the frightening properties of zero: multiply anything by zero, and it, too, turns to nothing. Independently, Mayans in the Americas developed their own zero to assist in the study of astronomy.