The main work of Brahmagupta, Brahmasphuta-siddhanta (The Opening of the Universe), written in the year c.628, contains some remarkably advanced ideas, including a good understanding of the mathematical role of zero, rules for manipulating both negative and positive numbers, a method for computing square roots, methods of solving linear and some quadratic equations, and rules for summing series,… (More on Brahmasphutasiddhanta)