The Indian astronomer and mathematician of the fifth century A.D., Aryabhata I lived and worked in Kusumapura near present-day Patna in Bihar. His greatest work is Aryabhatiya , which he wrote in when he was 23 years old. Aryabhatiya is a scholarly treatise in Sankrit on mathematics and astronomy.

Using the Sanskrit alphabets, he invented an ingenious system to express numbers on the decimal-place value model. This facilitated him to give astronomical constants and numerical data in a highly condensed form so that they could be easily memorized. Aryabhata I formulated the rules for extraction of square and cube roots by the arithmetical method which are used all over the world even today. The mathematical part of Aryabhatiya deals with important topics like geometrical figures and their properties, arithmetic progression and geometrical progression as well as simple simultaneous and Quadratic equations. It also gives rules and methods for construction of trigonometric sine tables in which sine and cosine are known as Jya and Koti-jaya.

Besides all this Aryabhata gave accurate approximation for PI (3.1416) and introduced into trigonometry the versed sine function. He was the first Indian astronomer to state that the earth is spherical and rotates on its axis. He explained that the apparent daily east-west motion of the sun, moon, planets and stars is due to the rotation of the earth from west to east.