Names of the days of the week the "first day". This convention is also found in some Austronesian languages whose speakers were converted to Christianity by European missionaries. In Slavic languages, some of the names correspond to numerals after Sunday: compare Russian "vtornik" "Tuesday" and "vtoroj" "the following", "chetverg" "Thursday" and "chetvertyj" "the fourth", "pyatnitsa" "Friday" and "pyatyj" "the fifth"; see also the Notes. In Standard Chinese, the week is referred to as the cycle of the stars (). The modern Chinese names for the days of the week are based on a simple numerical sequence. The word for "week" (which is literally translated to "star day")
Determination of the day of the week enter a self-contained function for converting a Gregorian date into a numerical day of the week. It preserves neither y nor d, and returns 0 = Sunday, 1 = Monday, etc. Shortly afterwards, Hans Lachman streamlined their algorithm for ease of use on low-end devices. As designed originally for four-function calculators, his method needs fewer keypad entries by limiting its range either to A.D. 1905-2099, or to historical Julian dates. It was later modified to convert any Gregorian date, even on an abacus. On Motorola 68000-based devices, there is similarly less need of either processor registers or opcodes, depending on