598-670

Indian astronomer and mathematician whose discussions of number theory prefigured ideas now accepted in mathematics. His Brahmasphutasiddhanta (628), translated as The Opening of the Universe, defined zero as the result obtained when a number is subtracted from itself—by far the best definition of zero up to that time. Brahmagupta also provided rules for "fortunes" and "debts" (positive and negative numbers), and used a place-value system much like that which exists today. In addition, The Opening of the Universe offered an algorithm for computing square roots, a method for solving quadratic equations, and rudimentary forms of algebraic notation.