Doomsday Algorithm

The Doomsday Algorithm gives the day of the week for any date (and you can do it in your head)

Added 1994-02-22, Updated 2011-02-28 with examples for 2011

Overview

The Doomsday Algorithm is presented in sections. Links are provided in the top right corner of each section.

To learn the Doomsday Algorithm, read the sections in the following order:

• February 28 or 29: Doomsday is the last day of February

• Even Months: April, June, August, October, and December (months 4, 6, 8, 10, and 12)

• Odd Months: March, May, July, September, and November (months 3, 5, 7, 9, and 11)

• 2011 Calendar: the current year calendar, highlighting the Doomsday in each month

• Other Years: how to apply the Doomsday Algorithm to other years in the 1900s and 2000s

• Other Centuries: extending the Doomsday Algorithm to other centuries

• The Hand: Dr. Conway's shortcut method

• Origins: the creation of the Doomsday Algorithm by Dr. John Horton Conway

• Links: Doomsday Algorithm resources on the Web for additional information

Have fun!