Determination of the day of the week Correction for Leap Year gives "3". Answer, "Wednesday". Since 23 February 1676 (counting February as the second month) is, for Carroll, the same day as Gregorian 4 March 1676, he fails to arrive at the correct answer, namely "Friday," for an Old Style date that on the Gregorian calendar is the same day as 5 March 1677. Had he correctly assumed the year to begin on the 25th of March, his method would have accounted for differing year numbers - just like George Washington's birthday differs - between the two calendars. It is noteworthy that those who have republished Carroll's
Determination of the day of the week his collected works in 1927. Gauss' method was applicable to the Gregorian calendar. He numbered the weekdays from 0 to 6 starting with Sunday. He defined the following operation: The weekday of 1 January in year number is where is the remainder after division of by , or modulo . This formula was also converted into graphical and tabular methods for calculating any day of the week by Kraitchik and Schwerdtfeger. Another variation of the above algorithm likewise works with no lookup tables. A slight disadvantage is the unusual month and year counting convention. The formula is where For example,