From: Dr John Stockton <jrs@merlyn.demon.co.uk>
Subject: Re: Results of my test: Re: Friday 13th, try it yourself
Date: 1996/09/26
Date: 1996-09-26T00:00:00+00:00 [thread overview]
Message-ID: <5bxuvOAdKcSyEwne@merlyn.demon.co.uk> (raw)
In-Reply-To: 52bmft$f3l@news1.halcyon.com
In article <Pine.SOL.3.91.960925162108.6568A-100000@serv1.jump.net> of
Wed, 25 Sep 1996 16:25:19 in comp.lang.pascal.misc, Lee Crites
<adonai@jump.net> wrote:
>
>For the most part, I've ignored this friday the 13th thread. However,
>something someone said got my interest. Basically the statement was that
>the same date 400 years later would fall on the same day. I thought I'd
>check it out and see. Unfortunately, it did not work on the dates I
>checked.
SNIP
Too complex. Just consider 400 years
400 * 365 Taking all years as ordinary
+ 100 but every fourth is leap
- 4 apart from the centuries
+ 1 except for every fourth.
=========
146097 ;
* 1/7 => 20871.0 = integer weeks in 400 years.
The calendar therefore repeats every 400 years.
This calculation can be done in one's head, without even a calculator.
In 400 years there are 4800 months each containing one 13th. Some are
Sunday, some ... ...Saturday; but 4800/7 is not an integer, so the 13ths
cannot be evenly distributed among the days of the week.
I think it is now necessary to do a little real work; there are 14 types
of year (Leap or not, starting Sun .. Sat), and the number of each type
in 400 years can be counted; and each type contributes a certain number
of 13ths.
It might be easier to consider the year as starting on March 1st; there
are now only 7 types of year for 13th-counting.
--
John Stockton, Surrey, UK. JRS@merlyn.demon.co.uk Turnpike v1.12 MIME
http://www.merlyn.demon.co.uk/
next prev parent reply other threads:[~1996-09-26 0:00 UTC|newest]
Thread overview: 66+ 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 ` James Giles
1996-09-18 0:00 ` Andrew Gierth
1996-09-18 0:00 ` Luke Chao
1996-09-18 0:00 ` James Giles
1996-09-18 0:00 ` Norman H. Cohen
1996-09-19 0:00 ` Andrew Gierth
1996-09-19 0:00 ` Daniel J. Long
1996-09-21 0:00 ` Ken Pizzini
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
1996-09-19 0:00 ` Norman H. Cohen
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 ` 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 ` Dik T. Winter
1996-10-02 0:00 ` Ken Pizzini
1996-09-26 0:00 ` Dr John Stockton [this message]
1996-09-26 0:00 ` Lee Crites
1996-09-26 0:00 ` John Winters
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 ` Adam Beneschan
1996-09-27 0:00 ` Glen Clark
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
1996-09-25 0:00 ` Friday 13th, try it yourself (was Language Wars..) Barrie Walker
1996-09-26 0:00 ` Jim Shapiro
1996-09-23 0:00 ` 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 ` 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
1996-09-24 0:00 ` language wars (results 13 September) last posting Andrew Gierth
1996-09-24 0:00 ` Art Schwarz
-- strict thread matches above, loose matches on Subject: below --
1996-10-03 0:00 Results of my test: Re: Friday 13th, try it yourself James Gillespie
1996-10-03 0:00 ` Paul Skoczylas
1996-10-03 0:00 ` Daan Sandee
1996-10-03 0:00 ` Dr John Stockton
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