SIMPLIFIED RULES 19 The number of mean civil days elapsed at the beginning of the mean solar year = 12 x 30 x (solar years elapsed) + (11 + 389/6000) x (solar years elapsed) (5+29/36+43/72000) x (solar years elapsed) = 30 x (solar months elapsed + mean intercalary months obtained in stanza 22) + mean intercalary days obtained in stanza 22 --- (5x solar years elapsed + residual mean omitted lunar days obtained in stanza 23). Therefore, the number of mean civil days elapsed on the first day of mean Caitra (or true Caitra)¹ = 30 x (solar months elapsed + mean intercalany months obtain- ed in stanza 22) (5xsolars years elapsed + residual mean omitted lunar days obtained in stanza 23). When these civil days are increased by one and divided by seven, the remainder of the division counted with Friday gives the day on which Caitra begins. In the above rule the author has avoided big numbers by dividing by seven at every stage. His rule is therefore easy to apply in practice. A rule for finding the the number of mean omitted lunar days occurring since the fall of the mean omitted lunar day just before the beginning of mean Caitra : 26(ii). Increase the number of (lunar) days (elapsed since the beginning of Caitra) by the number of (mean lunar) days elapsed (at the beginning of Caitra) since the fall of a mean omitted lunar day, and divide that (sum) by 64: the quotient gives the number of (mean) omitted lunar days (which have occurred since the mean omitted lunar day occurring before the beginning of Caitra) : A rule for finding the number of mean lunar days lying between the beginning of mean Caitra and the beginning of the mean solar year (called "the subtractive"): ¹ The first day of true Caitra may sometimes differ from that of mean Caitra by one day.
