Determination of the day of the week in the year row (07) is located in column G. The letter in the century row (13) and column G is E, so the day of the week is Friday. January 1 corresponds to G, G in the year row (00) corresponds to F in the century row (20), and F corresponds to Saturday. A pithy formula for the method: ""Date letter (G), letter (G) is in year row (00) for the letter (F) in century row (20), and for the day, the letter (F) become weekday (Saturday)"". Use 17 (in the Gregorian century row, column C) and 83 (in
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