Determination of the day of the week determined for the latter part of the analysis. By using a given day August 13, 2009 which was a Thursday as a reference, with "Base" and "n" being the number of days and weeks it has been since 01/01/0001 to the given day, respectively and "k" the day into the given week which must be less than 7, "Base" is expressed as Knowing that a year divisible by 4 or 400 is a leap year while a year divisible by 100 and not 400 is not a leap year, a software program can be written to find the number of
Determination of the day of the week week is where the positive modulus is chosen. The value of is obtained from the following table: The value of is obtained from the following table, which depends on the calendar. For the Gregorian calendar, For the Julian calendar, Charles Lutwidge Dodgson (Lewis Carroll) devised a method resembling a puzzle, yet partly tabular in using the same index numbers for the months as in the "Complete table: Julian and Gregorian calendars" above. He lists the same three adjustments for the first three months of non-leap years, one 7 higher for the last, and gives cryptic instructions for finding the rest;