Hack #43: Calculate Any Weekday

Quickly calculate the day of the week for any date of the Gregorian calendar \x96 useful for scheduling appointments and meetings!

Additions and Suggestions

Concrete ideas to modify and expand this hack go here.

Discussion

Freeform discussion of this hack goes here.

Links

• Lewis Carroll's algorithm: http://www.cs.usyd.edu.au/~kev/pp/TUTORIALS/1b/carroll.html
• CalendarFeat page on Mentat Wiki
• The World Calendar: http://personal.ecu.edu/mccartyr/world-calendar.html

Errata

Page 167 Line 6 erase 'divide the century by 4,' Line 7 replace 'sevens' by 'fours' The example should be.. Thus:

20 mod 4 equals 0 3 - 0 equals 3 2 times 3 equals 6

Hack Author

Ron Hale-Evans

Return to Main Book Page

This is a page for a hack from the book MindPerformanceHacks by Ron Hale-Evans.