Determination of the day of the week ISO 8601. The day designated with 7 may also be counted as "0", by applying the arithmetic modulo 7, which calculates the remainder of a number after division by 7. Thus, the number 7 is treated as 0, 8 as 1, 9 as 2, 18 as 4 and so on. If Sunday is counted as day 1, then 7 days later (i.e. day 8) is also a Sunday, and day 18 is the same as day 4, which is a Wednesday since this falls three days after Sunday. The basic approach of nearly all of the methods to calculate the
German Unity Day in East Germany, even with the name "Day of the German Unity". Since 1963, it was proclaimed by the President of the Federal Republic as "National Day of Memorial of the German People". However by the mid-1960s as hope faded that the two Germanies would ever be re-united, this date became more of a holiday and opportunity to drink than a day to consider national unity. In the year 1990, the "Day of German Unity" was celebrated twice, on this date and on October 3. In East Germany, the Founding Day in 1949 would be celebrated on 7 October as