Number geeks in the United States and Canada are celebrating a rare quirk in the calendar today. But most of the rest of the world will have to wait until July for a similar event.

Today’s date is, in the system used in the US, 05-07-09. That’s one of just six days in each century which have three consecutive odd numbers.

The date wouldn’t attract much attention it it weren’t for the efforts of Ron Gordon, a California school teacher and lover of numerical quirks. He’s set up a Web site with ideas for celebrating the occasion with a $579 prize for the best entry. (Presumably he won’t use a similar prize format on 11-13-15.)

Gordon is better known for establishing Square Root Day, in which the date and the month multiply to make the last two digits of the year. Gordon first brought this to media attention on Sept. 9,  1981 and appeared in the news again on both Jan. 1, 2001 and Feb. 2, 2004.

What Gordon is dubbing ‘Odd Day’ is not only a rarer event but, unlike Square Root Day, is not applicable worldwide. Aside from the US and Canada, only around half a dozen countries arrange their dates with the month first. In much of the rest of the world, the next Odd Day won’t be until July 5.

Countries using the ‘month second’ system have one fewer Odd Day each century as, unlike in the US, 11-13-15 doesn’t exist. However, the imbalance may be addressed this century as Gordon has already said he doesn’t think it would be appropriate to seek any publicity on 9/11 in 2013.

Some countries use the pattern year-month-day, which is also the standard method for computer dating as it guarantees numbers in chronological order will also be in numerical order. However, it appears all of these countries always write the year in full, meaning Odd Day will be lost on them.

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Entry was posted on Thursday, May 7th, 2009 at 7:20 pm under Uncategorized.

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