October 2013
Intermediate to advanced
753 pages
63h 57m
English
A perpetual calendar lets you find the day of the week for any date in any year. Because January 1 may fall on any of the seven days of the week and may be a leap or nonleap year, 14 different calendars are possible. The number next to each year corresponds to one of the 14 calendars. Calendar 4 will be used in 2014; calendar 5 will be used in 2015; calendar 13 will be used in 2016; calendar 1 will be used in 2017.

