I nearly let today slip past without recognising it as October the 10th, 2010 -- 10/10/10. I've always been interested in co-incidences like that, ever since I could read a calendar. Sequential numbers, triple numbers, numbers that spell stuff in 13375P33K, that kind of thing.
In fact, today is the tenth of only twelve triple-numbers in the 21st century! Since there are only twelve months in a Gregorian year, only the first twelve years of any particular century apply to the triple-numbers. The first was January the 1st, 2001 -- 1/1/01. The last will be December the 12th, 2012 -- 12/12/12.
I remember 6/6/06 because my quasi-goth mate, Jonas, from high school identified it as the Devil's Day (666 being the mark of the beast). There won't be another such day for 94 years! Hopefully by Devil's Day 2106, Zephram Cochrane or someone of his ilk will have successfully tested the first faster-than-light propulsion system.
Also going out the door for 100 years are the sequentially-numbered dates. Days like 01/02/03 or 08/09/10. December the 11th, 2013 -- 11/12/13 -- will be the final number sequence for 88 years (the next being February 1, 2103). Of course, if you use the American dating sequence, the final day for you will be December the 13th, 2014 ('cos Yankees put the date down month/day/year, whilst everyone else puts it down day/month/year).
Also, talking of random calendar stuff, I totally missed this century's Mario Month! In the dating sequence used everywhere but the US, March 2010 appeared as MAR/10! I was consciously aware of Mario Day, but Mario Month slipped my notice... I still had a radio programme at that time, too! Talk about one's excuse for having an all-Nintendo OST programme!
Anyway, if you're feeling depressed at the prospect of losing your sequentially-numbered dates and triple-numbers, consider the following. There are numerous other obscure mathematics to look forward to.
Take, for example, a Fibonacci sequence: 0,1,1,2,3,5 (the sequence is done by adding the next number to the previous one -- 0+1=1, 1+1=2, 2+1=3, 3+2=5, et cetera). Fibonacci Day will be on 01/12/35 (either December 1st or January 12th, 2035).
Next, prime numbers: in the non-American dating sequence, May 23rd, 2071 (23/5/71) will be Prime Day. In the American sequence, though, Prime Day will fall upon February 3rd, 2057 (2/3/57).
We can't forget the highly cototient numbers, either! In the non-American sequence, August 24th, 2023 (24/8/23) is Cototient Day. However, the US will have to wait 59 more years for Cototient Day, as the American sequence puts it on February 4th, 2082 (2/4/82)... at that rate, one may as well wait until January 1st, 2101.
If one happens to use the American sequence exclusively, though, Pi Day will be quite a grand day in 2015 -- March 14th, 2015 (3/14/15) expresses more digits of the Pi decimal than any other such day since 1592 (in which the year could be displayed in full and still be valid: 3/14/1592).
If you still need reassurance, though, look up integer sequences on Wikipedia. There are loads more that you can use to make yourself look either really smart or really lonely.
