Determination of the day of the week day of the week begins by starting from an ‘anchor date’: a known pair (such as January 1, 1800 as a Wednesday), determining the number of days between the known day and the day that you are trying to determine, and using arithmetic modulo 7 to find a new numerical day of the week. One standard approach is to look up (or calculate, using a known rule) the value of the first day of the week of a given century, look up (or calculate, using a method of congruence) an adjustment for the month, calculate the number of leap years
German Unity Day choice to commemorate the reunification could have been the day the Berlin Wall came down: 9 November 1989, which coincided with the anniversary of the proclamation of the German Republic in 1918, and the defeat of Hitler's first coup in 1923. However, 9 November was also the anniversary of the first large-scale Nazi-led pogroms against Jews in 1938 ("Kristallnacht"), so the day was considered inappropriate as a national holiday. (See November 9 in German history.) Therefore, 3 October 1990, the day of the formal reunification, was chosen instead and replaced the "Day of German Unity" on 17 June, the national