The day of the week (numbered according to for Sunday, for Monday, etc.) for a given day of the month ,
month , and year can be determined from the simple equation
A more complicated form is given by
Month | |
January | 1 |
February | 4 |
March | 3 |
April | 6 |
May | 1 |
June | 4 |
July | 6 |
August | 2 |
September | 5 |
October | 0 |
November | 3 |
December | 5 |
Gregorian | |
Century | |
15, 19, 23 | 1 |
16, 20, 24 | 0 |
17, 21, 25 | 5 |
18, 22, 26 | 3 |
Julian | |
Century | |
00, 07, 14 | 5 |
01, 08, 15 | 4 |
02, 09, 16 | 3 |
03, 10, 17 | 2 |
04, 11, 18 | 1 |
05, 12, 19 | 0 |
06, 13, 20 | 6 |
Year | Y | ||||||||
00 | 06 | 17 | 23 | 28 | 34 | 45 | 0 | ||
01 | 07 | 12 | 18 | 29 | 35 | 40 | 46 | 1 | |
02 | 13 | 19 | 24 | 30 | 41 | 47 | 2 | ||
03 | 08 | 14 | 25 | 31 | 36 | 42 | 3 | ||
09 | 15 | 20 | 26 | 37 | 43 | 48 | 4 | ||
04 | 10 | 21 | 27 | 32 | 38 | 49 | 5 | ||
05 | 11 | 16 | 22 | 33 | 39 | 44 | 50 | 6 | |
51 | 56 | 62 | 73 | 79 | 84 | 90 | 0 | ||
57 | 63 | 68 | 74 | 85 | 91 | 96 | 1 | ||
52 | 58 | 69 | 75 | 80 | 86 | 97 | 2 | ||
53 | 59 | 64 | 70 | 81 | 87 | 92 | 98 | 3 | |
54 | 65 | 71 | 76 | 82 | 93 | 99 | 4 | ||
55 | 60 | 66 | 77 | 83 | 88 | 94 | 5 | ||
61 | 67 | 72 | 78 | 89 | 95 | 6 |
See also Friday the Thirteenth
References
Kraitchik, M. ``The Calendar.'' Ch. 5 in
Mathematical Recreations. New York: W. W. Norton, pp. 109-116, 1942.
Uspensky, J. V. and Heaslet, M. A. Elementary Number Theory. New York: McGraw-Hill, pp. 206-211, 1939.
Vardi, I. Computational Recreations in Mathematica. Reading, MA: Addison-Wesley, pp. 237-238, 1991.
© 1996-9 Eric W. Weisstein