From: andrewg@microlise.co.uk (Andrew Gierth)
Cc: Norman H Cohen <ncohen@watson.ibm.com>
Subject: Re: language wars (results 13 September) last posting
Date: 1996/09/19
Date: 1996-09-19T00:00:00+00:00 [thread overview]
Message-ID: <uf3f0fmmrh.fsf@zen.microlise.co.uk> (raw)
In-Reply-To: 51bv60$8d@pheidippides.axion.bt.co.uk
>>>>> "Norman" == Norman H Cohen <ncohen@watson.ibm.com> writes:
> Andrew Gierth wrote:
>> Useless (but true) factoid:
>>
>> The 13th day of the month is more often Friday than any other day
>> of the week.
Norman> I apologize for the off-topic posting (especially when it is
Norman> cross-posted to so many newsgroups, and thus off so many
Norman> topics at once), but it should be pointed out, before this
Norman> becomes an urban legend, that this "factoid" is patently
Norman> false!
Oh dear. I don't have alt.folklore.urban on my server, or I might take
this discussion there; in the absence of any obvious other place to
direct followups to, we will have to stay off-topic for the time
being. Email might be a good move...
Norman> In any 2800-year cycle, the 13th will come out on each day of
Norman> the week the same number of times. In fact, this is true of
Norman> any 28-year cycle that does not include a century year that
Norman> is not a leap year (e.g. 1800, 1900, 2100, 2200).
You have missed, however, the fact that the calendar repeats every *400*
years, not every 2800. 400 years is 146097 days, which is 20871 weeks
precisely.
However, 400 years is 4800 months, which is *not* divisible by 7.
Therefore it is manifestly impossible for a specified day-of-the-month
to fall equally on all days of the week. It so happens that the 13th
falls most often on Friday.
Skeptics are invited to write a program to do the calculation for
themselves.
--
Andrew Gierth (andrewg@microlise.co.uk)
"Ceterum censeo Microsoftam delendam esse" - Alain Knaff in nanam
next prev parent reply other threads:[~1996-09-19 0:00 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
1996-09-13 0:00 language wars (results 13 September) last posting Roy Gardiner
1996-09-13 0:00 ` William Clodius
1996-09-13 0:00 ` Peter Seebach
1996-09-21 0:00 ` Robert Dewar
1996-09-21 0:00 ` Robert Dewar
1996-09-16 0:00 ` Robert Fahey
1996-09-18 0:00 ` Norman H. Cohen
1996-09-18 0:00 ` James Giles
1996-09-18 0:00 ` Andrew Gierth
1996-09-18 0:00 ` Luke Chao
1996-09-18 0:00 ` James Giles
1996-09-19 0:00 ` Daniel J. Long
1996-09-21 0:00 ` Ken Pizzini
1996-09-24 0:00 ` Art Schwarz
1996-09-26 0:00 ` Matthew D. Healy
1996-09-29 0:00 ` Randy MacDonald
1996-10-03 0:00 ` galina.kasminskaya
1996-10-03 0:00 ` Dave Tholen
1996-09-26 0:00 ` Ken Pizzini
1996-09-29 0:00 ` Paul Gilmartin
1996-09-21 0:00 ` Ken Pizzini
1996-09-19 0:00 ` Norman H. Cohen
1996-09-19 0:00 ` Andrew Gierth [this message]
1996-09-20 0:00 ` John Girash
1996-09-20 0:00 ` John Girash
1996-09-20 0:00 ` Friday 13th, try it yourself (was Language Wars..) Clinton Pierce
1996-09-21 0:00 ` Russell Mosemann
1996-09-21 0:00 ` Russell Mosemann
1996-09-25 0:00 ` Barrie Walker
1996-09-26 0:00 ` Jim Shapiro
1996-09-25 0:00 ` Ken Pizzini
1996-09-25 0:00 ` Results of my test: Re: Friday 13th, try it yourself Lee Crites
1996-09-25 0:00 ` William Clodius
1996-09-27 0:00 ` Dik T. Winter
[not found] ` <52qpqt$1b3l@ilx018.iil.intel.com>
1996-10-02 0:00 ` Ken Pizzini
1996-10-02 0:00 ` Dik T. Winter
1996-09-26 0:00 ` Dr John Stockton
1996-09-26 0:00 ` Lee Crites
1996-09-26 0:00 ` Adam Beneschan
1996-09-27 0:00 ` Glen Clark
1996-09-26 0:00 ` Daan Sandee
1996-09-26 0:00 ` Jeff Drummond
1996-09-30 0:00 ` Ray Dunn
1996-09-26 0:00 ` John Winters
1996-09-27 0:00 ` CHI Research, Inc.
1996-09-27 0:00 ` Lee Crites
1996-09-28 0:00 ` John Winters
1996-09-30 0:00 ` Adam Beneschan
1996-10-01 0:00 ` Mike McCarty
1996-09-26 0:00 ` Dr John Stockton
[not found] ` <199609302101.JAA04610@kauri.vuw.ac.nz>
1996-09-30 0:00 ` Lee Crites
1996-09-23 0:00 ` Friday 13th, try it yourself (was Language Wars..) Matthew D. Healy
1996-09-23 0:00 ` Dik T. Winter
1996-09-25 0:00 ` Paul Gilmartin
1996-09-22 0:00 ` Dr John Stockton
1996-09-23 0:00 ` Randy MacDonald
1996-09-23 0:00 ` Dik T. Winter
1996-09-25 0:00 ` John Harper
1996-09-25 0:00 ` jupiter
1996-09-23 0:00 ` Dr John Stockton
1996-09-24 0:00 ` language wars (results 13 September) last posting Andrew Gierth
1996-09-24 0:00 ` Art Schwarz
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