(DelawareOnline.com) -- If mathematics is the language in which the universe and the Earthspeak to us, then the diminutive constant pi would be an importantcomponent for that language.

"That's a very good way oflooking at math and pi," said Tom Fernsler, of the Math ScienceEducational Resource Center at the University of Delaware. "Everythingtoday that's made that is round or requires a calculation involving acircle, sphere or curved surface involves the use of pi."

It'seven got its own "Day." March 14 is designated as Pi Day, as thecalendar day representation of 3/14 matches the first three digits of pi(3.14).

That'sjust the tip of the geeky iceberg, but we'll circle back to that in amoment. It was Greek geek Archimedes who first correctly identified theratio of a circle's circumference to its diameter as 22/7.

"Everycircle regardless of size contains precisely that ratio," saidFernsler. "If there is any other ratio calculated other than 22/7 forthe spherical entity you are measuring, then it's not a circle."

Inother words, an oval or an ellipse does not have a ratio of 22/7, andmay be considered circular, but are most definitely not circles. But22/7 is but a crude representation of the precise measure of pi.

"Pi is an irrational number," Fernsler explained. "That means its decimal representation does not end, nor is it repeated."

Forexample, 1/2 is .5 decimally stated. 1/8 is .125. Both end and containno repetition of decimal places. Such numbers are called "rational"numbers. The fraction 1/3, however, is .3333333, etc. Its decimalequivalent repeats and doesn't end. That makes it an "irrational"number. ("Rational" is a mathematical term and does not in any waysuggest a rational number to be sane, or an irrational number to beinsane.)

Pi is irrational, and that's where the fun begins, aslong as fun for you includes memorizing and reciting pi out tothousands of decimal places. That turns out to be one of the many eventsthat have been taking place in Princeton, N.J., each year on March 14.

"Theidea came from doing something to commemorate Albert Einstein'sbirthdate of March 14," said Mimi Omiecinski, founder of Princeton's PiDay, now in its fifth year. She was surprised how that inaugural eventcaught on. "We would have been happy with a handful of attendees," saidOmiecinski. "But 1,500 people filled the library building on a day aNor'easter was pounding the area."

This year's events over asix-day period, which are expected to draw a crowd of 6,000 plus, willinclude the pi recitation contest, along with an Einstein look-a-likecontest, pie- (not pi) eating and judging contests and a walking tour ofEinstein's neighborhood.

"It's a celebration during which a geek can feel like a rock star," said Omiecinski.

ProfessorBarry Renner, chair of the Department of Mathematics at WilmingtonUniversity, puts Pi Day into a larger, more significant context.

"Anything which popularizes math and helps to show it as something fun is a worthwhile activity."

**The skinny on pi**

•**World famous. **Pi is the most recognized mathematical constant in the world.

•**Around the Earth. **If the circumference of the Earth werecalculated using pi rounded to only the ninth decimal place, an error ofno more than one quarter of an inch in 25,000 miles would result.

•**Pi baby. **Albert Einstein was born on Pi Day (3/14/1879) in Ulm, Germany.

•**Are you a piphilologist? **Piphilology is the study andcreation of mnemonic techniques for memorizing the never-ending stringof decimal digits of pi. The technique of memorizing lines of poetry(known as a "piem") or prose is one of the best known. When the lettersin each of the words in the phrase "How I want a drink, alcoholic ofcourse, after the heavy lectures involving quantum mechanics" arecounted, they correspond to the numerical 3.14159265358979 (carrying pito 14 decimal places) and you become a hit at geek parties.

•**Is pi carried to one trillion digits overkill?** Whilemodern computers are capable of calculating pi to one trillion decimalplaces, it doesn't do much practically for science. According tomathematicians Jörg Arndt and Christoph Haenel, 39 digits are sufficientto perform most calculations, because that is the accuracy necessary tocalculate the volume of the known universe with a precision of oneatom.

•**Pi cheers. **School spirit at the Massachusetts Instituteof Technology has been memorialized in the cheer: "Cosine, secant,tangent, sine 3.14159."

•**You can't get there from here. **UD's Tom Fernsler says piwas essential to the calculations that landed a man on the moon."Reaching the moon required the rendezvous of two separate spacecrafts,"Fernsler said. "That meant the intersection of two spherical orbitsrequired calculations involving pi." In other words, without Archimedes,there would be no Neil Armstrong.

•**Pyramid scheme. **Egyptologists have been fascinated forcenturies by by evidence that suggests the Great Pyramid at Giza seemsto approximate pi. The vertical height of the pyramid has the samerelationship to the perimeter of its base as the radius of a circle hasto its circumference.

•**Pi and the arts.** "The Little Constant That Could" haswound its way into artistic expression. Carl Sagan used the digits of pito suggest a secret message from God in his novel "Contact." The 1998movie "Pi" concerns a mathematician looking for a number to explain themeaning of existence. The Oscar-winning film "Life of Pi" actually hasnothing to do with the constant's calculation or possible hiddenmeanings. (Though the movie does feature a cool CGI tiger that probablyused pi in its design computer calculations.)

•**The granddaddy of all Pi Days? **San Francisco'sExploratorium is hosting its 25th annual Pi Day. Its website(www.exploratorium.edu/pi/index.html) states the annual celebration hasgrown into an international and online event. Included are pie-makingand -throwing exhibitions.

•**Trekkie pi. **In the Star Trek episode "Wolf in the Fold,"Spock foils the evil computer by commanding it to "compute to the lastdigit the value of pi."

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