Determination of the day of the week *104804 + 4, "n" = 104804 and "k" = 4 which implies that August 13, 2009 is the fourth day into the 104805th week since 01/01/0001. 13 August 2009 is Thursday; therefore, the first day of the week must be Monday, and it is concluded that the first day 01/01/0001 of the calendar is "Monday". Based on this, the remainder of the ratio "Base/7", defined above as "k", decides what day of the week it is. If "k" = 0, it's Monday, "k" = 1, it's Tuesday, etc. Determination of the day of the week The determination of the day
Islamic calendar Islamic calendar (see section below) in which odd-numbered months have thirty days (and also the twelfth month in a leap year) and even months have 29. In Arabic, the "first day" of the week corresponds with Sunday of the planetary week. The Islamic weekdays, like those in the Hebrew and Bahá'í calendars, begin at sunset. The Christian liturgical day, kept in monasteries, begins with vespers (see vesper), which is evening, in line with the other Abrahamic traditions. Christian and planetary weekdays begin at the following midnight. Muslims gather for worship at a mosque at noon on "gathering day" (, meaning