Ethiopia thirteenth month. The Ethiopian months begin on the same days as those of the Coptic calendar, but their names are in Ge'ez. Like the Julian calendar, the sixth epagomenal day—which in essence is a leap day—is added every four years without exception on 29 August of the Julian calendar, six months before the Julian leap day. Thus, the first day of the Ethiopian year, 1 Mäskäräm, for years between 1901 and 2099 (inclusive), is usually 11 September (Gregorian), but falls on 12 September in years before the Gregorian leap year. Also, a seven- to eight-year gap between the Ethiopian and
Burmese calendar will contain 354 days, as opposed to the solar year of ~365.25 days. Therefore, some form of addition to the lunar year (of intercalation) is necessary. The overall basis for it is provided by cycles of 57 years. Eleven extra days are inserted in every 57 years, and seven extra months of 30 days are inserted in every 19 years (21 months in 57 years). This provides 20819 complete days to both calendars. As such, the calendar adds an intercalary month ( ) in leap years ( ) and sometimes also an intercalary day ( ) in great leap years