Bramhagupta (597-668)Bramhagupta (597-668) - Mathematician and astronomer from the northwest Indian town of Bhinmal in the state of Rajhastan. Although broadly gifted in science, he is most famous for developing a numerical value for zero (0). It seems so basic today, but until then, zero had simply been a abstract concept meaning a lack of any amount with no symbol attributed to it. But Bramhagupta didn't stop there. With a value for zero now established, he was able to work backwards and also developed the concept of negative numbers. This opened up the field to more complex equations, and eventually lead to higher forms of math. There was an observatory in Bramhagupta's time, and he was in charge of it. It was in Ujjain, which was the center of math and science in India. He wrote several works, the most famous being the Brāhmasphuţasiddhānta in 628 (the other names are just about as long, so you can understand why I left them off). His conclusions are written in poetic form and do not contain any formulas, so we have no idea how he reached them. By the 8th century his work spread to the Abbasid Caliphate, which was expanding in the region and had many scholars who were active in collecting knowledge. It's because he was so highly regarded that his conclusions survive.