Ujjain, with its tradition of scholarship, had been an important centre of mathematic learning since the 4th century CE. Two of the most famous mathematical brains of ancient India, Varahamihira (505-587 CE) and Brahmagupta (598-665 CE) belong to the Ujjain school of mathematics.
Varahamihira is said to have been one of the nine jewels of navaratnas in the court of Chandragupta II. Though he was born as Mihira. It is popularly held that overwhelmed by his genius, Vikramaditya conferred upon him the name Varaha (boar). Thereafter he come to be known as Varahamihira. Varahamihira is best known for his Panchasiddhantika (the Five Astronomical Conons, 575 CE) and Brihat Samhita.
Panchasiddhantika summarises the five astronomical treatises that came before it – Surya Siddhanta, Romaka Siddhanta, Pauliso Diddhanta, Vasishtha Siddhanta and Paitomaha Siddhanta. Some scholars even hold that Panchasiddhantika is one of the most important sources for the history of Hindu astronomy before the time of Aryabhata II.
This treatise is the oldest known work where zero appears in arithmetical operations.