# Celebrate 25 years of Pi Day

PiDay.org

PiDay.org offers e-cards for the occasion, including this LOLcat perspective. Click to send an e-card.

The most famous irrational number, pi, is being factored into a whole smorgasbord of silliness on 3/14.

On one level, the date is just an excuse for high geekery, ranging from eating mathematically meaningful pies to marching in a circular pi procession. On a deeper level ... well, who needs an excuse to celebrate one of nature's most mysterious numbers?

In differently curved universes, the ratio of a circle's circumference to its diameter might be something other than 3.14159 and some change. But in our universe, the digits that describe that ratio have never come to an end or shown a repeating pattern, even though pi's value has been computed to a length of 10 trillion digits. The irrationality of pi has popped up as a theme in a goodly number of books and movies through the years, including "Contact" (the book) and "Pi" (the movie). Pi's continuing hold on our imagination is definitely something worth celebrating.

Here are a few ways to mark the day:

• Celebrate the 25th-anniversary Pi Day with the Exploratorium in San Francisco, where the festivities reach their peak at 3/14, 1:59 p.m. PT. The Exploratorium in San Francisco is where it all began in 1988, when physicist Larry Shaw organized the first public celebration of Pi Day. There'll also be a Pi Day party on Exploratorium Island in the Second Life virtual world, starting at 8 p.m. PT / SLT.
• Send a Pi Day e-card. The Web site for Pi Day offers discussions and videos about pi, books and merchandise to buy, suggested activities and information about the why of pi.
• Look around for local events, such as Pi Day Princeton or the Maryland Science Center's Pi Day party. Chances are that your local science center is doing something to celebrate the day ... and if not, maybe you can convince the ticket-takers to reduce the cost of admission to \$3.14, just this once.
• Celebrate Albert Einstein's birthday, which also falls on March 14. Our "Century of Einstein" special report is just as insightful today as it was when we published it in 2005 to mark the centennial of the great physicist's "miracle year."
• Make your plans for Tau Day, the holiday for people who think pi is passé. Tau is twice the value of pi, and some mathematicians say that makes their equations easier to juggle. If you're a tau touter, June 28 (6/28) is your special day. And if you don't follow the American style of stating dates, you might be more comfortable celebrating pi on July 22 (22/7), a date that evokes a fraction close to the irrational value of pi.

"Pi Day, Pi Day" ... get down with a spoof video from 2011.

Anything to add? If you have other ways to celebrate Pi Day, let us know in your comment below.

More pi peculiarity:

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.

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# Discuss this post

The best fraction I've ever found I read in a BASIC programming book a long time ago (in a galaxy far, far away) which was 355/113 and that is accurate to about 7 digits (good for quick, dirty calculations).

#1 - Wed Mar 14, 2012 3:56 AM EDT

Is there a PHI Day? Wasn't that the first IRRATIONAL NUMBER? 1.6108!

#1.1 - Wed Mar 14, 2012 6:26 PM EDT

(Peter Riddle) wasn’t that the first IRRATIONAL NUMBER? 1.6108!

This is wrong in the same way Pi is Limited (see comment circa #11 below), The Golden Ratio is Limited, perhaps I should say special.

If I take the Fibonacci series, generated like this 0, 1, 1, 2, 3, 5, 8, 13, 21, … where each successive term is the sum of the previous terms.

It produces a series of numbers that for the first few numbers, at least, corresponds to what is seen in nature at a high level of coincident where adjacency is important for growth and reproduction. However because there are so many natural examples in the same number range, there is little interest in documenting this because it would include the whole of cell and plant evolution. (An infinite series of its own.)

If in a simple spread sheet you divide a in the series number, by its prior entry the number rapidly converges to the Golden Ratio: 1.6108… Or,

If in the same sheet you divide a number by the next successive number that number rapidly converges to 0.6108... Both the Golden Ratio and its Inverse have the same decimal digits. The Golden Ratio(s) produce the most attractive rectangles and geometric proportion attractive to the eye. The ratio can easily be represented like Pi by a rational number as an integer ratio. However by adding one half to this value and square the results produces 5, or the square root of 5 less one half is the Golden Ratio.

The Ancient saw that if you could produce a number in a finite number of steps it was rational number, if took an infinite number of steps it was irrational. This leaves you with the problem of figuring the value of irrational numbers when only the rational part was useful.

Home work: Turing marked the 100 year since his birth, and recent papers show his genius, exercise: if is not necessary to calculate to infinity to represent nature (atom will due?) or to even crank Turing machines to produce faster computers where would you define the practical boundary. Bonus: Nomination to the Noble Prize.

#1.2 - Wed Mar 14, 2012 7:58 PM EDT

Ahem...

May please I be excused now? My brain is full...

• 1 vote
#1.3 - Wed Mar 14, 2012 10:57 PM EDT

Irrational exuberance? Why not transcendence?

#2 - Wed Mar 14, 2012 10:31 AM EDT

Ok, as a public service I'll go ahead and say it and get it over with.

I hope you appreciate my sacrifice. This only passes for wit on "Hee-Haw".

"Pi r squared.

No, idjit, Pie are round, Cornbread are square."

Ok, there, it's done, now we can get on with our lives.

#3 - Wed Mar 14, 2012 11:25 AM EDT

Don't forget "brownies are square" as well...

• 1 vote
#3.1 - Wed Mar 14, 2012 4:14 PM EDT

Whaddya git when you divide a pumpkin's circumference by the pumpkin's diameter?

Pumpkin pi.

#3.2 - Wed Mar 14, 2012 5:03 PM EDT

I'm waiting until 2015 at 9:26 am to celebrate. Much more accurate. 3.14.15, 9:26. 3/14 at 1:59 is premature.

#4 - Wed Mar 14, 2012 11:57 AM EDT

My favorite math equation has always been 'pie are squared' - but that's dumb, everyone knows pie are round! Stupid mathematicians....

• 1 vote
#5 - Wed Mar 14, 2012 12:45 PM EDT

#5.1 - Wed Mar 14, 2012 1:01 PM EDT

It would appear my sacrifice was for nothing.

Oh, the humanity!

#5.2 - Wed Mar 14, 2012 1:30 PM EDT

Don't worry, Skip, your sacrifice wasn't in vain! Don't you hear the lamentation of the women?

Oh wait.

#5.3 - Wed Mar 14, 2012 3:16 PM EDT

God is telling us we make our pies wrong....

#5.4 - Wed Mar 14, 2012 7:43 PM EDT

I heard that pi r cubed, or at least 4/3 of them are

#5.5 - Wed Mar 14, 2012 9:27 PM EDT

What about those rectangular-cut pizza pies? They taste fine, but it's geometrically incorrect

• 1 vote
#6 - Wed Mar 14, 2012 1:09 PM EDT

42

#7 - Wed Mar 14, 2012 1:20 PM EDT

I'm going to get some french silk pie right now!

#8 - Wed Mar 14, 2012 1:54 PM EDT

-----Direct Quote from the Fortran manual for Xerox computers

The primary purpose of the DATA statement is to give names to constants; instead of referring to PI as 3.141592653589797, at every appearance, the variable PI can be given that value with a DATA statement, and used instead of the longer form of the constant. This also simplifies modifying the program, should the value of PI change.

The funny thing is, the concept actually makes a lot of sense. The author just chose a very poor example of something that "might change."

#9 - Wed Mar 14, 2012 6:50 PM EDT

Byron Raum,

Actually pi's value has changed over the years. I was taught as a kid (well before calculators) to use 22/7 as the value of pi. At least one southern state legally defined the value as 3, not sure I would trust their engineering. The early 8-bit (Commodore, TRS, Apple) computers used varying approximations.

#9.1 - Wed Mar 14, 2012 7:28 PM EDT

In 1897 the Indiana state legislature made a go at changing the value of pi implicitly with a bill that asserted that the circle can be squared. The implied value of pi was 4.

That's almost as dumb as the stuff that goes on in Washington on a daily basis. Regards....

• 1 vote
#9.2 - Wed Mar 14, 2012 8:31 PM EDT

Indiana tried to change it to 3.2 in 1897.

• 1 vote
#10 - Wed Mar 14, 2012 7:23 PM EDT

Two Pi is better than one Pi, pie in the sky leaves the stomach empty.

Applying Pi to a Pie or any perfect circle has some limitations, if the edge is examined at the scale of atoms, the count around the edge will be an integer number, and likewise a count across the circle will also be an integer. The ration of these two integers is a rational number; however Pi is an irrational number. If we down to scales at the quantum level, we will not get to integer values again, so we may have to use the irrational form.

There are at least 17 ways to calculate Pi that spring up naturally, expressed as infinite series where each successive term gets closer and closer.

Pi pops up all the time as scientist develops various formulas, Euler’s Formula, Euler’s Identity are among the most productive.

Euler's formula, e^i*x = cos x + i * sin x

Euler's Identity, e^i*Pi + 1 = 0

The (i) in many equations that represent the complexity of real world, represents (-1^1/2) or the square root of minus one. If you were interested in quantum mathematics, complex arithmetic, fractals or electrodynamics then it is advisable to learn this material in your teens. If you encounter ideas in graduate school, it would be too late, since most of the applications would have passed you by, and you could bypass more than a few course.

References: Provide two narratives for the mathematically inclined one conceptual and the other historical.

Simon And Schuster, New York, 1956, The World of Mathematics, James R. Newman, 4 Vols

Oxford University Press, 1972, Mathematical Thought from Ancient to Modern Times, Morris Kline,

10^-16 is smallest confirmed diameter Pi has rational limits.

Some commenter above quipped (Peter Riddle) wasn’t that the first IRRATIONAL NUMBER? 1.6108!

This is wrong in the same way Pi is Limited, The Golden Ratio is Limited, perhaps I should say special.

If I take the Fibonacci series, generated like this 0, 1, 1, 2, 3, 5, 8, 13, 21, … where each successive term is the sum of the previous terms.

It produces a series of numbers that for the first few numbers, at least, corresponds to what is seen in nature at a high level of coincident where adjacency is important for growth and reproduction. However because there are so many natural examples in the same number range, there is little interest in documenting this because it would include the whole of cell and plant evolution. (An infinite series of its own.)

If in a simple spread sheet you divide a in the series number, by its prior entry the number rapidly converges to the Golden Ratio: 1.6108… Or,

If in the same sheet you divide a number by the next successive number that number rapidly converges to 0.6108... Both the Golden Ratio and its Inverse have the same decimal digits. The Golden Ratio(s) produce the most attractive rectangles and geometric proportion attractive to the eye. The ratio can easily be represented like Pi by a rational number as an integer ratio. However by adding one half to this value and square the results produces 5, or the square root of 5 less one half is the Golden Ratio.

The Ancient saw that if you could produce a number in a finite number of steps it was rational number, if took an infinite number of steps it was irrational. This leaves you with the problem of figuring the value of irrational numbers when only the rational part was useful.

Home work: Turing marked the 100 year since his birth, and recent papers show his genius, exercise: if is not necessary to calculate to infinity to represent nature (atom will due?) or to even crank Turing machines to produce faster computers where would you define the practical boundary. Bonus: Nomination to the Noble Prize.

#11 - Wed Mar 14, 2012 7:55 PM EDT

Of course, this 'holiday' pretty much only exists in the US where dates are abbreviated to mm/dd/yyyy whereas in most of the rest of the world it follows a more logical dd/mm/yyyy.

#12 - Wed Mar 14, 2012 8:26 PM EDT

e^(iπ)+1=0

#13 - Wed Mar 14, 2012 8:54 PM EDT

I have computed all the digits of pi. They are 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. Ha ha.

I wonder if the ratio of a particular digit to the total number of digits in the limit is 1/10. Who knows?

• 1 vote
#14 - Wed Mar 14, 2012 9:11 PM EDT

﻿﻿﻿﻿"Computer. This is a Class-A compulsory directive. Compute, to the last digit, the value of pi." - Spock

• 1 vote
#15 - Sun Mar 18, 2012 11:36 AM EDT

The method of determining when to celebrate pi does not follow scientific methods of reporting data. This is because the units of time are changed within the report. If the month is to be the unit of time, then the celebration should occur at 0.14159+ of a month past the beginning of March.

When this is converted to days, the value is 4.389+. This takes us to March 4 at 0.389 days past 12:00M. This takes us to 9.34 AM or 9:20 AM. For convenience I have not used all of the available digits, but any purists reading this can do the calc's to greater accuracy. Comments on this units-of-time concept are welcome.

#16 - Thu Mar 14, 2013 2:23 PM EDT

The American Mathematical Society @amermathsoc is having some fun on twitter with Pi Day. See my post below:

AmericanMathSociety ‏@amermathsoc

Pi Fall: Bond's loyalty is tested when arch enemy Tau steps in to challenge Pi's place as sacred number of the circle. #pimoviepitches

• 1 vote
#17 - Thu Mar 14, 2013 3:06 PM EDT

Marv C. wrote:

The method of determining when to celebrate pi does not follow scientific methods of reporting data. This is because the units of time are changed within the report. If the month is to be the unit of time, then the celebration should occur at 0.14159+ of a month past the beginning of March.

When this is converted to days, the value is 4.389+. This takes us to March 4 at 0.389 days past 12:00M. This takes us to 9.34 AM or 9:20 AM. For convenience I have not used all of the available digits, but any purists reading this can do the calc's to greater accuracy. Comments on this units-of-time concept are welcome.

The trouble with that sort of measurement attempt is that it simply isn't pedantic enough. One can't convert months to days, since different months are worth different amounts of days; if we were to celebrate e Day in this way, we would be computing the date as 0.71828*28 (or *29) days through February, clearly a different standard than you are applying to March. Clearly, then, your methodology does not convert 0.14159+ months into days but instead 0.14159+ Marches into days. 4 March at 9:34 AM is in fact only 0.14159 of a March, and not necessarily 3.14159 months. Sadly, months simply aren't good units of measurement when one is attempting to follow scientific methods of reporting data.

#18 - Thu Mar 14, 2013 3:09 PM EDT
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