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Topic: palindrome dates (Read 4189 times) |
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mikedagr8
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palindrome dates
« on: Jul 13th, 2007, 2:31am » |
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I am not sure if anyone has stated the answer yet, but my solution is 19/11/1191. I figure this because i am not able to make the first 2 numbers and last 2 numbers in the date any smaller (days and decade and indivual year). If anyone is able to make a smaller date please give me a clue, and i will figure it out.
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towr
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Re: palindrome dates
« Reply #1 on: Jul 13th, 2007, 2:40am » |
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The date format asked for is MMDDYYYY , so you have months and days reversed. Although, of course, it's no less interesting to find the last palindrome date in DDMMYYYY format.
Also I'm a bit confused that you seem to be asking for a smaller date, when the puzzle asks for the last before october 2nd 2001.
11/11/1111 is smaller, and 29/11/11/92 is larger (using DDMMYYYY format)
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Wikipedia, Google, Mathworld, Integer sequence DB
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mikedagr8
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Re: palindrome dates
« Reply #2 on: Jul 13th, 2007, 2:43am » |
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woopsy thanks. month first is different from where i come from, so it is natural for me to just think like that. And the 29.....92 well, i was just not thinking thanks for pointing that out.
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jaqqo
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Re: palindrome dates
« Reply #3 on: Sep 24th, 2007, 11:49am » |
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The latest date before 10/02/2001 that I can come up with is 12/31/1321.
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Pheasant
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Re: palindrome dates
« Reply #4 on: Nov 15th, 2007, 3:51pm » |
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08/31/1380 would be slightly better still.
- there can't be anything in the 15th to 20th century, as months can only have a 0, 1, 2, or 3 as their first digit. "00" is no valid day so there's also nothing in year 2000.
- This leaves the 14th century. The last two digits of the year must result in a valid month when reversed, which happens "first" in 1390. September only has 30 days though, so 09/31/1390 is invalid, leaving 08/31/1380 as the next possible time.
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| « Last Edit: Nov 15th, 2007, 3:52pm by Pheasant » |
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Joe Fendel
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Re: palindrome dates
« Reply #5 on: Nov 19th, 2007, 12:18pm » |
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on Nov 15th, 2007, 3:51pm, Pheasant wrote:| This leaves the 14th century. The last two digits of the year must result in a valid month when reversed, which happens "first" in 1390. September only has 30 days though, so 09/31/1390 is invalid, leaving 08/31/1380 as the next possible time. |
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Ah, but the modern Gregorian calendar wasn't adopted until the 16th century! In the 14th century, the Julian calendar was still in widespread use and...
Oh, wait, that doesn't affect the answer in the slightest. 
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