Names of the days of the week Meiji era. In China, with the founding of the Republic of China in 1911, Monday through Saturday in China are now named after the luminaries implicitly with the numbers. Sunday comes first in order in calendars shown in the table below. In the Judeo-Christian or Abrahamic tradition, the first day of the week is Sunday. Biblical Sabbath (corresponding to Saturday), when God rested from , made the day following Sabbath the first day of the week (corresponding to Sunday). Seventh-day Sabbaths were sanctified for celebration and rest. After the week was adopted in early Christianity, Sunday remained the first day
Determination of the day of the week the intended design objective. The tabular forerunner to Tøndering's algorithm is embodied in the following K&R C function. With minor changes, it was adapted for other high level programming languages such as APL2. Posted by Tomohiko Sakamoto on the comp.lang.c Usenet newsgroup in 1992, it is accurate for any Gregorian date. IBM's Rata Die method requires that one knows the "key day" of the proleptic Gregorian calendar i.e. the day of the week of January 1, AD 1 (its first date). This has to be done to establish the remainder number based on which the day of the week is