Dear Heloise: I have read in your column several hints for using old calendars. Here is another: Simply use them again!
There are only 14 ways that the calendar can fall - seven because the year can begin on any day of the week and seven more for leap years.
Calendars for 1995 will also be valid in 2006. This year, we can use calendars from 1968, and in 1997 we can reuse calendars from 1986.
To see if an old calendar is valid, simply check that any date falls on the correct day of the week. Also check whether the calendar is for a leap year. If you already have all 14 calendars, you’ll never need to buy a calendar again. - Mark Camann, San Antonio, Texas
Wow, you really got us thinking and it just may be worth keeping those old calendars to use again. - Heloise