Sabbath a synonym of midnight-to-midnight "Saturday" (literally, Saturn's day in at least a dozen languages): this is a simplification of the use of "Sabbath" in other religious contexts, where the two do not coincide. (Using midnight instead of sundown as delimiter dates back to the Roman Empire.) In over thirty other languages, the common name for this day in the seven-day week is a cognate of "Sabbath". "Sabbatini", originally "Sabbadini", often "Sabatini", etc., is a very frequent Italian name form ("Sabbatos" is the Greek form), indicating a family whose ancestor was born on Saturday, Italian "sabato"; "Domenico" indicated birth on Sunday.
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