diamond geezer

 Wednesday, December 12, 2012

12/12/12

It's a very special day today. All the twelves. So special that everyone looking at today's date will say "woo, look at that", even Americans. Three numbers the same is incredibly rare, indeed so exceptional that we only get twelve such dates a century...
1/1/01, 2/2/02, 3/3/03, 4/4/04, 5/5/05, 6/6/06, 7/7/07, 8/8/08, 9/9/09, 10/10/10, 11/11/11, 12/12/12
The last three on that list are the most special of all - triplets of double-digit numbers - with 11/11/11 the ultimate perfect match. But today's your lot. You've now lived through the entire list, and you'll never see another.

Almost as very-special are dates consisting solely of identical digits. We had three of these last year, but again such dates are very rare. There are only a dozen in every century, with the next almost a decade hence.
1/1/11, 11/1/11, 1/11/11, 2/2/22, 22/2/22, 3/3/33, 4/4/44, 5/5/55, 6/6/66, 7/7/77, 8/8/88, 9/9/99
If the twenty-four dates above form the calendar's Premiership, then simple counting sequences are the Championship. There are twenty-three such triplets, eleven ascending and twelve descending.
1/2/03, 2/3/04, 3/4/05, 4/5/06, 5/6/07, 6/7/08, 7/8/09, 8/9/10, 9/10/11, 10/11/12, 11/12/13
2/1/00, 3/2/01, 4/3/02, 5/4/03, 6/5/04, 7/6/05, 8/7/06, 9/8/07, 10/9/08, 11/10/09, 12/11/10, 13/12/11
These are in-your-face enough for most people to notice, and are usually the signal for a flurry of tweets saying "woo, it's precisely 07:08:09 10/11/12" or the like. But again they're really quite rare. And, with the exception of one final straggler in 52 weeks time, they too have all passed by.

If considering digits rather than numbers, however, then there are more ascending and descending sequences to celebrate. Not many more, but fourteen still to look forward to.
1/2/34, 2/3/45, 12/3/45, 3/4/56, 23/4/56, 4/5/67, 5/6/78, 6/7/89
3/2/10, 4/3/21, 5/4/32, 6/5/43, 7/6/54, 8/7/65, 9/8/76
And then there are several additional dates of arithmetical interest. Precisely additional sometimes, for that category of dates where the day plus the month equals the year. Take for example the first day of last month, which was 1/11/12. You might not have got excited about it, but 1+11=12 was good enough to elevate this particular date into the special addition category. There were eleven such dates this year, one in every month except December, and there'll be twelve more every year from 2013 to 2030. Here are the 'addition' dates for 2013...
12/1/13, 11/2/13, 10/3/13, 9/4/13, 8/5/13, 7/6/13, 6/7/13, 5/8/13, 4/9/13, 3/10/13, 2/11/13, 1/12/13 (and 353 other dates this century)
It's no coincidence that there are 365 addition dates altogether. Every single day-plus-month combination adds to give a possible year, with the exception of Leap Day 29th February where 29/2/31 doesn't exist. Less than 20% of the 21st century's addition dates have passed, so we still have plenty more of these to enjoy.

Let's move on to subtraction. Every year from 2000 to 2019 sees twelve subtractable dates, one per month, then they gradually fade away. From the first of the century on 1/1/00 to the last on 31/1/30, there are 299 of these in total. Here, for example, are all the 'subtraction' dates for 2013...
14/1/13, 15/2/13, 16/3/13, 17/4/13, 18/5/13, 19/6/13, 20/7/13, 21/8/13, 22/9/13, 23/10/13, 24/11/13, 25/12/13
Americans with their month/day order saw no subtraction dates in 2012, indeed will see no more this century. But we've got another on Christmas Eve, because twenty-four subtract twelve is twelve, and then a further 143 to go.

My favourites are the multiplicative dates. They're a bit more subtle, a bit less obvious, so they make me smile even if most people never notice them. A simple times table like 6/2/12 might be clear enough, but who'd spot 26/3/78 or 13/7/91 unless they had a particular mathematical bent? There are 212 such dates altogether, a little better spread out than all the other dates we've considered so far. Here, for example, are all the 'multiplication' dates for the second half of the century...
25/2/50, 10/5/50, 5/10/50, 17/3/51, 26/2/52, 13/4/52, 27/2/54, 18/3/54, 9/6/54, 6/9/54, 11/5/55, 5/11/55, 28/2/56, 14/4/56, 8/7/56, 7/8/56, 19/3/57, 20/3/60, 15/4/60, 12/5/60, 10/6/60, 6/10/60, 5/12/60, 21/3/63, 9/7/63, 7/9/63, 16/4/64, 8/8/64, 13/5/65, 22/3/66, 11/6/66, 6/11/66, 17/4/68, 23/3/69, 14/5/70, 10/7/70, 7/10/70, 24/3/72, 18/4/72, 12/6/72, 9/8/72, 8/9/72, 6/12/72, 25/3/75, 15/5/75, 19/4/76, 11/7/77, 7/11/77, 26/3/78, 13/6/78, 20/4/80, 16/5/80, 10/8/80, 8/10/80, 27/3/81, 9/9/81, 28/3/84, 21/4/84, 14/6/84, 12/7/84, 7/12/84, 17/5/85, 29/3/87, 22/4/88, 11/8/88, 8/11/88, 30/3/90, 18/5/90, 15/6/90, 10/9/90, 9/10/90, 13/7/91, 23/4/92, 31/3/93, 19/5/95, 24/4/96, 16/6/96, 12/8/96, 8/12/96, 14/7/98, 11/9/99, 9/11/99
Some years do better than others for multiplication. 2060 and 2072 appear in the list six times (as do 2012, 2030, 2036 and 2048), but the best year for multiplicative dates is 2024 with seven. Only twenty-one years have none at all, and it'll be 2037 before we reach the first of those.

At the bottom of the arithmetical ranking comes division. These dates aren't quite so exciting, nor indeed as common, because dividing a day by a month generally leaves a remainder. Many are boring divisions with a 1 in them, like 12/1/12, which ought to be excluded because they've already appeared in the multiplication list. But there are 58 other dates unique to division, of which only 26/2/13 and 28/2/14 have yet to occur.

Here's how many special dates of each type I think there are in a century (being careful not to double-count any repeats when calculating the total).

type of special datefirst and lastin a century
equal numbers1/1/01 to 12/12/1212
repeated digits1/1/11 to 9/9/9912
ascending sequence1/2/03 to 11/12/1311
descending sequence 2/1/00 to 13/12/1112
ascending digits1/2/34 to 6/7/898
descending digits3/2/10 to 9/8/767
addition1/1/02 to 31/12/43365
subtraction1/1/00 to 31/1/30299
multiplication1/1/01 to 9/11/99212
division2/2/01 to 28/2/1458
 total993

So, if my calculations are correct, every century contains a total of 993 special calendar dates. That means a day picked at random has about a 2½% chance of being special, according to my subjective definition of what special is.

And which is the most special year of the century for special dates? Why, it's 2012, with 33 altogether.
11/1/12, 12/1/12, 13/1/12, 6/2/12, 10/2/12, 14/2/12, 24/2/12, 4/3/12, 9/3/12, 15/3/12, 3/4/12, 8/4/12, 16/4/12, 7/5/12, 17/5/12, 2/6/12, 6/6/12, 18/6/12, 5/7/12, 19/7/12, 4/8/12, 20/8/12, 3/9/12, 21/9/12, 2/10/12, 22/10/12, 1/11/12, 10/11/12, 23/11/12, 1/12/12, 12/12/12, 24/12/12
Eleven additions, twelve subtractions, six multiplications, a division, one ascending sequence, and today's glorious triple. No other year can beat that.

In this, the calendar's most special year of the century, today is the most special day of the year. Twelve twelve twelve. Enjoy this freakish repeat while you can, because you'll never see its like again.


<< click for Newer posts

click for Older Posts >>


click to return to the main page


...or read more in my monthly archives
Jan24  Feb24  Mar24
Jan23  Feb23  Mar23  Apr23  May23  Jun23  Jul23  Aug23  Sep23  Oct23  Nov23  Dec23
Jan22  Feb22  Mar22  Apr22  May22  Jun22  Jul22  Aug22  Sep22  Oct22  Nov22  Dec22
Jan21  Feb21  Mar21  Apr21  May21  Jun21  Jul21  Aug21  Sep21  Oct21  Nov21  Dec21
Jan20  Feb20  Mar20  Apr20  May20  Jun20  Jul20  Aug20  Sep20  Oct20  Nov20  Dec20
Jan19  Feb19  Mar19  Apr19  May19  Jun19  Jul19  Aug19  Sep19  Oct19  Nov19  Dec19
Jan18  Feb18  Mar18  Apr18  May18  Jun18  Jul18  Aug18  Sep18  Oct18  Nov18  Dec18
Jan17  Feb17  Mar17  Apr17  May17  Jun17  Jul17  Aug17  Sep17  Oct17  Nov17  Dec17
Jan16  Feb16  Mar16  Apr16  May16  Jun16  Jul16  Aug16  Sep16  Oct16  Nov16  Dec16
Jan15  Feb15  Mar15  Apr15  May15  Jun15  Jul15  Aug15  Sep15  Oct15  Nov15  Dec15
Jan14  Feb14  Mar14  Apr14  May14  Jun14  Jul14  Aug14  Sep14  Oct14  Nov14  Dec14
Jan13  Feb13  Mar13  Apr13  May13  Jun13  Jul13  Aug13  Sep13  Oct13  Nov13  Dec13
Jan12  Feb12  Mar12  Apr12  May12  Jun12  Jul12  Aug12  Sep12  Oct12  Nov12  Dec12
Jan11  Feb11  Mar11  Apr11  May11  Jun11  Jul11  Aug11  Sep11  Oct11  Nov11  Dec11
Jan10  Feb10  Mar10  Apr10  May10  Jun10  Jul10  Aug10  Sep10  Oct10  Nov10  Dec10 
Jan09  Feb09  Mar09  Apr09  May09  Jun09  Jul09  Aug09  Sep09  Oct09  Nov09  Dec09
Jan08  Feb08  Mar08  Apr08  May08  Jun08  Jul08  Aug08  Sep08  Oct08  Nov08  Dec08
Jan07  Feb07  Mar07  Apr07  May07  Jun07  Jul07  Aug07  Sep07  Oct07  Nov07  Dec07
Jan06  Feb06  Mar06  Apr06  May06  Jun06  Jul06  Aug06  Sep06  Oct06  Nov06  Dec06
Jan05  Feb05  Mar05  Apr05  May05  Jun05  Jul05  Aug05  Sep05  Oct05  Nov05  Dec05
Jan04  Feb04  Mar04  Apr04  May04  Jun04  Jul04  Aug04  Sep04  Oct04  Nov04  Dec04
Jan03  Feb03  Mar03  Apr03  May03  Jun03  Jul03  Aug03  Sep03  Oct03  Nov03  Dec03
 Jan02  Feb02  Mar02  Apr02  May02  Jun02  Jul02 Aug02  Sep02  Oct02  Nov02  Dec02 

jack of diamonds
Life viewed from London E3

» email me
» follow me on twitter
» follow the blog on Twitter
» follow the blog on RSS

» my flickr photostream

twenty blogs
our bow
arseblog
ian visits
londonist
broken tv
blue witch
on london
the great wen
edith's streets
spitalfields life
linkmachinego
round the island
wanstead meteo
christopher fowler
the greenwich wire
bus and train user
ruth's coastal walk
round the rails we go
london reconnections
from the murky depths

quick reference features
Things to do in Outer London
Things to do outside London
Inner London toilet map
20 years of blog series
The DG Tour of Britain
London's most...

read the archive
Mar24  Feb24  Jan24
Dec23  Nov23  Oct23  Sep23
Aug23  Jul23  Jun23  May23
Apr23  Mar23  Feb23  Jan23
Dec22  Nov22  Oct22  Sep22
Aug22  Jul22  Jun22  May22
Apr22  Mar22  Feb22  Jan22
Dec21  Nov21  Oct21  Sep21
Aug21  Jul21  Jun21  May21
Apr21  Mar21  Feb21  Jan21
Dec20  Nov20  Oct20  Sep20
Aug20  Jul20  Jun20  May20
Apr20  Mar20  Feb20  Jan20
Dec19  Nov19  Oct19  Sep19
Aug19  Jul19  Jun19  May19
Apr19  Mar19  Feb19  Jan19
Dec18  Nov18  Oct18  Sep18
Aug18  Jul18  Jun18  May18
Apr18  Mar18  Feb18  Jan18
Dec17  Nov17  Oct17  Sep17
Aug17  Jul17  Jun17  May17
Apr17  Mar17  Feb17  Jan17
Dec16  Nov16  Oct16  Sep16
Aug16  Jul16  Jun16  May16
Apr16  Mar16  Feb16  Jan16
Dec15  Nov15  Oct15  Sep15
Aug15  Jul15  Jun15  May15
Apr15  Mar15  Feb15  Jan15
Dec14  Nov14  Oct14  Sep14
Aug14  Jul14  Jun14  May14
Apr14  Mar14  Feb14  Jan14
Dec13  Nov13  Oct13  Sep13
Aug13  Jul13  Jun13  May13
Apr13  Mar13  Feb13  Jan13
Dec12  Nov12  Oct12  Sep12
Aug12  Jul12  Jun12  May12
Apr12  Mar12  Feb12  Jan12
Dec11  Nov11  Oct11  Sep11
Aug11  Jul11  Jun11  May11
Apr11  Mar11  Feb11  Jan11
Dec10  Nov10  Oct10  Sep10
Aug10  Jul10  Jun10  May10
Apr10  Mar10  Feb10  Jan10
Dec09  Nov09  Oct09  Sep09
Aug09  Jul09  Jun09  May09
Apr09  Mar09  Feb09  Jan09
Dec08  Nov08  Oct08  Sep08
Aug08  Jul08  Jun08  May08
Apr08  Mar08  Feb08  Jan08
Dec07  Nov07  Oct07  Sep07
Aug07  Jul07  Jun07  May07
Apr07  Mar07  Feb07  Jan07
Dec06  Nov06  Oct06  Sep06
Aug06  Jul06  Jun06  May06
Apr06  Mar06  Feb06  Jan06
Dec05  Nov05  Oct05  Sep05
Aug05  Jul05  Jun05  May05
Apr05  Mar05  Feb05  Jan05
Dec04  Nov04  Oct04  Sep04
Aug04  Jul04  Jun04  May04
Apr04  Mar04  Feb04  Jan04
Dec03  Nov03  Oct03  Sep03
Aug03  Jul03  Jun03  May03
Apr03  Mar03  Feb03  Jan03
Dec02  Nov02  Oct02  Sep02
back to main page

the diamond geezer index
2023 2022
2021 2020 2019 2018 2017
2016 2015 2014 2013 2012
2011 2010 2009 2008 2007
2006 2005 2004 2003 2002

my special London features
a-z of london museums
E3 - local history month
greenwich meridian (N)
greenwich meridian (S)
the real eastenders
london's lost rivers
olympic park 2007
great british roads
oranges & lemons
random boroughs
bow road station
high street 2012
river westbourne
trafalgar square
capital numbers
east london line
lea valley walk
olympics 2005
regent's canal
square routes
silver jubilee
unlost rivers
cube routes
Herbert Dip
metro-land
capital ring
river fleet
piccadilly
bakerloo

ten of my favourite posts
the seven ages of blog
my new Z470xi mobile
five equations of blog
the dome of doom
chemical attraction
quality & risk
london 2102
single life
boredom
april fool

ten sets of lovely photos
my "most interesting" photos
london 2012 olympic zone
harris and the hebrides
betjeman's metro-land
marking the meridian
tracing the river fleet
london's lost rivers
inside the gherkin
seven sisters
iceland

just surfed in?
here's where to find...
diamond geezers
flash mob #1  #2  #3  #4
ben schott's miscellany
london underground
watch with mother
cigarette warnings
digital time delay
wheelie suitcases
war of the worlds
transit of venus
top of the pops
old buckenham
ladybird books
acorn antiques
digital watches
outer hebrides
olympics 2012
school dinners
pet shop boys
west wycombe
bletchley park
george orwell
big breakfast
clapton pond
san francisco
thunderbirds
routemaster
children's tv
east enders
trunk roads
amsterdam
little britain
credit cards
jury service
big brother
jubilee line
number 1s
titan arum
typewriters
doctor who
coronation
comments
blue peter
matchgirls
hurricanes
buzzwords
brookside
monopoly
peter pan
starbucks
feng shui
leap year
manbags
bbc three
vision on
piccadilly
meridian
concorde
wembley
islington
ID cards
bedtime
freeview
beckton
blogads
eclipses
letraset
arsenal
sitcoms
gherkin
calories
everest
muffins
sudoku
camilla
london
ceefax
robbie
becks
dome
BBC2
paris
lotto
118
itv