7 Jun
2004
7 Jun
'04
1:02 a.m.
Under what circumstances exactly will a 50 year anniversary fall on the same day of the week as the original date?
If one ignores leap-year days, 50 years equals 2607 weeks and one day. So the anniversary will occur on the same weekday if there are 6,13,20,27,... leap days. But leap days occur almost every fourth year: there are always 11-13 of them in a 50-year span. We want 13. That happens when the date is not a leap day, occurs less than two years before a leap day, and does not occur less than 50 years before any "missing leap day": that is, March 1st of a century-year which is not a leap-year. -- Don Reble djr@nk.ca