Hack #43: Calculate Any Weekday

Quickly calculate the day of the week for any date of the Gregorian calendar – 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?.