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Author Topic: There were 5 Sundays in February 2004. When's the next time?  (Read 1045 times)

Offline P-Kasso2

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There were 5 Sundays in February 2004. When's the next time?
« on: 18 December, 2019, 04:35:22 PM »
I was knee-deep in the attic, idly leafing through some miscellaneous junk to throw away when, under layers of dust, I found an old calendar for 2004.
Flip flip.
And blow me down!   
There's February 2004 staring at me - with not 4 but 5 red Sundays!
5 Sundays in 29 days?
Is it normal for our shortest month to have 5 Sundays?
When is the next time?
« Last Edit: 11 February, 2020, 03:20:21 PM by P-Kasso2 »
"I live in hope"

Offline P-Kasso2

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Re: There were 5 Sundays in February 2004. When's the next time?
« Reply #1 on: 11 February, 2020, 03:16:23 PM »
I was knee-deep in the attic, idly leafing through some miscellaneous junk to throw away when, under layers of dust, I found an old calendar for 2004.
Flip flip.
And blow me down!   
There's February 2004 staring at me - with not 4 but 5 red Sundays!
5 Sundays?
Is it normal for our shortest month to have 5 Sundays?
When is the next time?

Here's the answer folks!  And it is surprising to say the least!  The next time there'll be 5 Sundays in our shortest month of February since 2004 is... not until 2032. 


This is according to the learned American mathematical website called The Math Forum which says...

"the next time there'll be 5 Sundays in February is 2032 - followed by 2060, 2088, 2128, 2156, 2184, 2224, 2252, 2280, 2320, 2348 and 2376."

And I say for all you maths boffins out there, The Math Forum also gives you a whole load of mathematical explanations as to why - most of which go straight over my aching head.  But they are all there just in case some bright spark on IA understands the maths on the website!  Here are just a few of the things The Math Forum says, such as...

"In order for there to be 5 Sundays in February, two things must
happen.  First, it must be a leap year.  Second, February 1st must
fall on a Sunday, so that the remaining four Sundays will fall on the
8th, 15th, 22nd and 29th.  This just happened in 2004, which I assume
prompted your question!

- and -

Now, if February 1st is a Sunday, then January 1st must have been on a
Thursday (you can confirm that with any calendar).  So an equivalent
question is asking how often January 1 occurs on a Thursday in a leap
year.

- and -

At first glance one would think that, since leap years are 1/4 of the
years, and Thursdays are 1/7 of the days, that the answer should be
1/28 of the years have that property.  In the Julian calendar, this is
the correct answer, and those years come exactly 28 years apart."


Etc, etc etc.

And that is just the easy part!  Happy reading on the website.


http://mathforum.org/library/drmath/view/64804.html
« Last Edit: 11 February, 2020, 03:30:18 PM by P-Kasso2 »
"I live in hope"