Ganita deals with observations and calculations for the casting of horoscopes (Jātaka). Ganita also deals with the mathematical calculations for computing calendars, seasons, eclipses, entry periods of planets, helical rising and settings of stars and other such matters. In earlier day’s the ancient rishi’s did not have modern and sophisticated types of equipment(s) as we now have. Hence, a student of Jyotiṣa had to learn the ganita part. Due to the many Jyotish software, the modern-day Jyotiṣa’s skip this part. However, the great Varahamihira cautioned that ‘any error in ganita is a heinous sin like the murder of a brahmana. The most famous books on ganita are ‘Surya Siddhanta’ and ‘Drik Sidhanta’