Determination of the day of the week row C) to find the dominical letter that is E. The letter for September 18 is B, so the day of the week is Thursday. Use 16 (in the Julian century row, column E) and 76 (in row D) to find the dominical letter that is A. February 23 is a "D" day, so the day of the week is Wednesday. In a handwritten note in a collection of astronomical tables, Carl Friedrich Gauss described a method for calculating the day of the week for 1 January in any given year. He never published it. It was finally included in
Names of the days of the week Sun and Moon ("sunnudagur" and "mánudagur" respectively), while dispensing with the names of the explicitly heathen gods in favour of a combination of numbered days and days whose names are linked to pious or domestic routine ("föstudagur", "Fasting Day" and "laugardagur", "Washing Day"). The "washing day" is also used in other North Germanic languages, but otherwise the names correspond to those of English. The ISO prescribes Monday as the first day of the week with ISO-8601 for software date formats. The Slavic, Baltic and Uralic languages (except Finnish and partially Estonian) adopted numbering but took Monday rather than Sunday as