Under what circumstances exactly will a 50 year anniversary fall on the same day of the week as the original date? Today (6 June 2004) is a Sunday, and so was 6 June 1954. Ignore all the old calendar stuff, let's say I'm only interested in this question for dates after 1800. There seem to be lots of web pages about "repeating calendar years" but that's not at all the same question since dates can agree on day of the week even when they differ on leap year status... I was asked this at a wedding anniversary party and stammered something about 100 year leap year cycles with 400 year exceptions but couldn't work out the general answer, at least with dance music playing Thane Plambeck 650 321 4884 office 650 323 4928 fax http://www.plambeck.org