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Wikipedia:Wikifun/Round 11/Answers/Question 8

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Well, this is easy to start but hard to finish.

According to 2002:

  • February 20 - In Reqa Al-Gharbiya, Egypt, a fire on a train injures over 65 and kills at least 370
  • February 20 - In most of the world, at 20:02 (8:02 PM) local time, date (written as day/month), time, and year are all 2002, making each of them alone, any two together, and the combination of all three, all palindromes.

(that is, in hh:mm DD/MM/YYYY, 20:02 20/02/2002, or in hh:mm MM/DD/YYYY, 20:02 02/20/2002)

Palindrome#Symmetry of dates and times is not much help, but there are websites and newspaper articles. For the Commonwealth, assuming we want full palindromicity of time, date, year and the whole thing, the previous occurrences would be:

  • 20:02 on 10 January 2002 (20:02 10/01/2002) (but I can't find the mayor)
  • 12:21 on 21 December 1221 (12:21 21/12/1221) (which is actually the 13th century, not the 12th century, but who is counting; and I'm not sure why 15:51 on 21 December 1551 (15:51 21/12/1551) does not count)

For the US. I'm not sure whether to use MM/DD/YYYY hh:mm or hh:mm MM/DD/YYY or even YYYY/MM/DD hh:mm. Assuming we use the first:

  • 20:01 on October 2 2001 (10/02/2001 20:01) (and the German composer is Franz Biebl)
  • 12:21 on December 21 1441 (12/21/1441 12:21) (this is in the 15th century, not the 14th century) (or, using hh:mm mm//dd/yyy possibly, 15:51 12/21/1551 (15:51 on December 21 1551) - again, though, this is the 16th century, not the 15th century)

For both together, 12:21 on December 21 1221 also works for the US (12:21 1221/12/21 12:21 or 12/21/1221 12:21 or whatever) but we have not got to 2021 yet, so you must be thinging of 11:11 on 11 November 1111 (11:11 11/11/1111 or 1111/11/11 11:11, etc). I guess the event 800 years later is The Great Blue Norther of 11/11/11 (on 11 November 1911).

(Started with Google search for "train accident 370" leads to 2002...) -- ALoan (Talk) 11:43, 8 December 2005 (UTC)[reply]

  • Well, you seem to have most of the required dates correctly and The Great Blue Norther is the event in question, so you can have 6 of the points. Well Done. Your reasoning isn't completely correct. For example, 10/02/2001 20:01 isn't palindromic. 4 points are available to whomsoever can neaten the answer up and should be able to tell me who the mayor is. Dmn 14:47, 8 December 2005 (UTC)[reply]

Emordnilap.

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Saw this was (answered partially), so I'm listing my partial answer.

First went to List_of_train_accidents and found "2002-02-20 - Al Ayatt train disaster, Egypt: A train packed to double capacity catches fire, 373 die.", so I figured it's palindrome dates, in this case 20/02/2002. UK: dd/mm/yyyy and USA: mm/dd/yyyy.

Figured on: 2001-02-10 (10/02/2001), so tried 10 February and found "# 2001 - Abraham Beame, Mayor of New York City (b. 1906)".

Guessed the previous was 1113-11-31 (31/11/1113).


Figured US was 2001-10-02 (10/02/2001) so looked up October_2 and found "2001 - Franz Biebl, German composer (b. 1906)"

Guessed the 14th century date was 1321-12-13 (12/13/1321). I was wrong, see below.

For when it occurred in both systems, I thought 2005-800=1205 so probably before then if event isn't eclipse. Guessed, 1111-11-11 (11/11/1111) +800 = 1911-11-11 so tried 11 February, no joy. Tried 1911, no joy.

Searched "palindrome dates" and found a link back to October_2 and found "2001 - First palindromic MM-DD-YYYY date since 1380-08-31." Went to palindrome, it's #Symmetry_of_dates_and_times isn't any help. — Jeandré, 2005-12-08t16:05z

Full Answer

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Between the two of you, you have it all.

  • In commonwealth countries, dates are written DD/MM/YYYY.
  • Googling for the train crash reveals the date 20 February 2002. If you spot the symmetry or read the 2002 article - it should have given the idea of looking for palindromic dates.
  • Since using the time gave the wrong century, and no dead Mayor, using just the day was the right thing to do.
  • Finding all possible previous 21st century dates is easy. It must be of the form ??/02 20??. The only correct answers are 20/02 2002 and 20/01 2001 <- when Abraham Beame died.
  • The previous one before this must be of the form ??/?1 1???. The earliest century to get a valid month is the 12th century: ??/11 11??. Counting back from 99 reveals 29/11 1192.
  • In the US, MM/DD/YYYY is the way to go
  • 20/02 2002 isn't a valid date, but 10/02 2001 is. On the 2 October page, there is confirmation you're on the right route.
  • Before this, require ??/?1 1???. The latest century here is the 14th: ??/31 13??. Counting back from 99, and unlike me originally, realising September has only 30 days, the answer is 08/31 1380.
  • Simultaniety occurs only when the year is itself palindromic, i.e. 11/11 1111 is the correct dates.
  • 800 years later The Great Blue Norther of 11/11/11 occurred. Dmn 16:38, 8 December 2005 (UTC)[reply]
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