please empty your brain below
And I love the time you posted this! Great work DG!

Michael | 12.12.12 - 12:23 a.m. | #

Are you going to post at 12:12 too, as well as 00:12?

Andrew | 12.12.12 - 12:40 a.m. | #

Everyone noticed Friday 11 November last year. It would have been even better on a Sunday, but you can't have everything.

Hmm, I wonder when 11 November xy11 is next on a Sunday...

Andrew | 12.12.12 - 12:42 a.m. | #

Sorry Andrew, the answer's never.

Thanks to the Gregorian Calendar, in a year ending in 11, November 11th can only ever fall on a Monday, Wednesday, Friday or Saturday.

diamond geezer | Homepage | 12.12.12 - 12:55 a.m. | #

No 11/11/11 in the second list?

dg writes: I'm attempting to count each date once, for its most special reason, so 11/11/11 is in the first list.

AC | 12.12.12 - 3:36 a.m. | #

Actually I see you haven't included any of the ones in the first list...

Seems to make "There are only a dozen in every century" wrong?

dg writes: The other dates in the first list don't have identical digits, just identical numbers.

AC | 12.12.12 - 3:38 a.m. | #

And it's my birthday. Which is far more important ;)

Kirk | 12.12.12 - 6:32 a.m. | #

Happy birthday Kirk! You're not 12, are you...?

THC | 12.12.12 - 7:24 a.m. | #

Part of the reason for picking the 10th of last month to get married was that it would be fairly hard for me to forget our anniversary.

Im glad we didn't pick today, because Hackney Town Hall were trying to squeeze in 12 ceremonies!

martin | 12.12.12 - 8:24 a.m. | #

Part of the reason for picking the 10th of last month to get married was that it would be fairly hard for me to forget our anniversary.

I'm glad we didn't pick today, because Hackney Town Hall were trying to squeeze in 12 ceremonies!

martin | 12.12.12 - 8:24 a.m. | #

Very interesting, but what about using the logical ISO date format, e.g. (YY)YYMMDD HH:MM:SS?

Next year's 08:09:10 on 11/12/13 isn't so special if it is written 131211 08:09:10.

It'll be must easier to twitter "Yeah, it's 131211 10:09:08" as I'll be at work by then, and not in the middle of dropping the kids of a kindergarden as would be the case at 08:09:10 :-)

Mark | 12.12.12 - 8:27 a.m. | #

This is all very interesting and I may sound like a spoilsport but surely we are in year 2012 rather than 12?

popartist | 12.12.12 - 9:17 a.m. | #

Well, 2012 is one of the names of the year we are in. 12 is another. 2012 may have special status because Little Dennis thought, wrongly, that Jesus was born that many years ago. Or because it's less ambiguous. But for numerological purposes, I reckon we should any faintly plausible system of numbering, whatever gives the most circumbobulous result.

Malcolm | 12.12.12 - 9:50 a.m. | #

How about the two years which are sequuencs of primes
5/7/11 and 7/11/13 ?

john | 12.12.12 - 9:51 a.m. | #

My 11 year old announced this morning that he plans to live to be 100, as he missed 01/01/01 the last time round!
My 13 year old is annoyed that she missed being born on 9/9/99 by arriving a few days early! :D

CornishCockney | 12.12.12 - 10:04 a.m. | #

What about a fibonacci sequence? Of course we're only limited to the first few numbers:

1,1,2,3,5,8,13

SDW | 12.12.12 - 10:31 a.m. | #

Aaargh. Surely if it was 12/12/12 Jesus would be looking forward to his birthday, staring shyly at boys and ordering more Oxy10.

Dan | 12.12.12 - 10:31 a.m. | #

OMG - finding out all these things about numbers is a bit like switching on to an episode of How!
Hmmm. Then there's odds and evens. I'm guessing the last all-odd date would have been 29/11/1999; and the last all-even one would've been 28/08/2008. It'll be another eight years till the next one.

Great post :)

RogerW | 12.12.12 - 11:23 a.m. | #

Your algorithms are a bit off - at least w.r.t. multiplication dates you lists 9/12/96 which doesn't appear to make sense.

dg writes: Fixed, thanks.

You also say that only 21 years have no multiplication dates - which I think is not true. We cannot have multiplicative dates on prime years except for during the first 31. There are 14 primes between 31 and 99:
37
41
43
47
53
59
61
67
71
73
79
83
89
97

In addition, years which are not primes but where it only has duplets where one of the factors is larger than 12 add to this list. This can only be doubles of primes:
74
82
86
94

Finally, there's an issue in that we cannot use 29 as a factor in February unless it is a leap year. So 29/2/58 does not work and leaves that year barren.

For a grand total of 20...

So, if my logic is right you only get a B- for your maths. Could do better.
Unless you are counting the year 2000, when (obviously) there was no 0th of the 0th. But that would be cheating!

I'll get my coat ; ^ )

Nice work !

Pedant | 12.12.12 - 11:32 a.m. | #

The best was ten years ago really when the date was one that can occur only once in a millennium that of 20/02/2002 :D That's my favorite one. (Can even have the time with it as well at 20:02)

Ady | 12.12.12 - 11:59 a.m. | #

14 (prime) + 4 (prime doublets) + 1 (non-leap 29 February in 2058) = 19

I think the condition for the prime doublets is one factor greater than 31, no? (not greater than 12 - 13/2/26 is ok)

But you also can't have 29/2/58, or 31/2/62.

So 2062 is an extra +1.

And you have to count either 2000 or 2100. Either way, it ends in 0. Another +1.

So that is 21, I think.

Andrew | 12.12.12 - 12:03 p.m. | #

O, the twelfth day of December ...

Sir Toby Belch | 12.12.12 - 12:12 p.m. | #

Damn! I get an F- for not being able to add 14 + 4 + 1...

And you are right, the prime doublet condition is "bigger than (28 for February or 29 for February in a leap year or 30 for A,J,S,N or 31 for J,M,M,J,A,O,D)"

Therefore, you get an A+ for spotting that 31/2/62 is also illegal.

I'll put my coat back.

Pedant | 12.12.12 - 12:28 p.m. | #

I stand in awe at getting your post out on the 12th second!!!

| 12.12.12 - 12:51 p.m. | #

The post was made in the 12th minute (not second)...

NLW | 12.12.12 - 2:54 p.m. | #

My favorites are palindromic: 19/9/1991 and 21/02/2012. Without working it out, I guess there's an even longer wait for one of them to turn up.

Rob | 12.12.12 - 3:59 p.m. | #

your next palindrome will arrive on 02/02/2020

timbo | 12.12.12 - 4:28 p.m. | #

Palindromic...that is the word-knew I would get it from DG or the comments.

Thanks!

Amused | 12.12.12 - 4:59 p.m. | #

It amuses me that people swap between a 2-digit year and the full 4-year digit year depending on which one suits the peculiar sequence of digits they're trying to impress people with at the time.

Doggie | 12.12.12 - 5:10 p.m. | #

C'mon, in eight days' time, at almost quarter past eight in the evening, we'll have 20:12 20/12/2012.

That's not too shabby!

Richard M | 12.12.12 - 7:19 p.m. | #

20:12 20/12/2012 ----- and a few hours later, the world will end

- or not.

timbo | 12.12.12 - 8:58 p.m. | #

From my "vaguely interesting" files: there was an item in my local paper about a lad turning 12 on 12/12/12. His best friend turned 11 last year on 11/11/11.

Great Aunt Annie | 12.12.12 - 9:23 p.m. | #

And what's really cool is that when I read the post there were 12 comments. I hoped people would stop posting so that it wouild stay at 12. Hey-ho.

RogerB | 13.12.12 - 9:29 a.m. | #

I was hoping that the number of comments would reach 12+12+12 (which it might!)

Bob Lindsay-Smith | 13.12.12 - 7:00 p.m. | #

Here's comment no.35 :)

Great Aunt Annie | 13.12.12 - 7:36 p.m. | #

@Bob, I was hoping that too, so I'm pleased to add comment no. 36...

What are the chances of it staying like this?

s | 14.12.12 - 10:36 a.m. | #

probably not very likely

amber | 14.12.12 - 7:28 p.m. | #











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