Determination of the day of the week not a Gregorian leap year, (but 19 in the Julian column indicates that it "is" a Julian leap year, as are all Julian "x"00 years). 20 indicates that 2000 is a leap year. Use Jan and Feb only in leap years. For determination of the day of the week (1 January 2000, Saturday) For determination of the dominical letter (2000, BA) For determination of the doomsday (2000, Tuesday) Note that the date (and hence the day of the week) in the Revised Julian and Gregorian calendars is the same from 14 October 1923 to 28 February AD 2800 inclusive and
Determination of the day of the week January 1, 2000. (year − 1 for January) formula_3 formula_4 Note: The first is only for a 00 leap year and the second is for any 00 years. The term mod 7 gives the values of months: The term mod 7 gives the values of years: The term mod 7 gives the values of centuries: Now from the general formula: formula_5; January 1, 2000 can be recalculated as follows: formula_6 formula_7 Kraitchik proposed two methods for calculating the day of the week. One is a graphical method. The other uses a formula that he credits to Gauss on p. 110: