Lunar calendar average length of the synodic month is days. Thus it is convenient if months generally alternate between 29 and 30 days (sometimes termed respectively “"hollow"” and “"full"”). The distribution of "hollow" and "full" months can be determined using continued fractions, and examining successive approximations for the length of the month in terms of fractions of a day. In the list below, after the number of days listed in the numerator, an integer number of months as listed in the denominator have been completed: These fractions can be used to construct a lunar calendar, or in combination with a solar calendar
Siṃha month of Karkaṭa, and followed by the solar month of Kanyā. The Simha month is called "Avani" in the Tamil Hindu calendar. The ancient and medieval era Sanskrit texts of India vary in their calculations about the duration of Simha, just like they do with other months. For example, the "Surya Siddhanta", dated to c. 400 CE, calculates the duration of Simha to be 31 days, 0 hours, 26 minutes and 48 seconds. In contrast, the "Arya Siddhanta" calculates the duration of the Simha month to be 31 days, 2 hours, 5 minutes and 31 seconds. The Indian solar month