 Pi is the most recognized mathematical constant in the world. Scholars often consider Pi the most important and intriguing number in all of mathematics.^{e}
 In the Star Trek episode “Wolf in the Fold,” Spock foils the evil computer by commanding it to “compute to last digit the value of pi.”^{d}
 Comedian John Evans once quipped: “What do you get if you divide the circumference of a jacko’lantern by its diameter? Pumpkin π.”^{d}
 Scientists in Carl Sagan’s novel Contact are able to unravel enough of pi to find hidden messages from the creators of the human race, allowing humans to access deeper levels of universal awareness.^{d}
 The symbol for pi (π) has been used regularly in its mathematical sense only for the past 250 years.^{c}
 During the famed O.J. Simpson trial, there were arguments between defense attorney Robert Blasier and an FBI agent about the actual value of pi, seemingly to reveal flaws in the FBI agent’s intellectual acumen.^{d}
 A Givenchy men’s cologne named Pi is marketed as highlighting the sexual appeal of intelligent and visionary men.^{h}
 We can never truly measure the circumference or the area of a circle because we can never truly know the value of pi. Pi is an irrational number, meaning its digits go on forever in a seemingly random sequence.^{f}
 Darren Aronofsky’s fascinating movie π (Pi: Faith in Chaos) shows how the main character’s attempt to find simple answers about pi (and, by extension, the universe) drives him mad. The film won the Directing Award at the 1988 Sundance Film Festival.^{g}



Both π and the letter p are the sixteenth letter in the Greek and English alphabets, respectively 


 In the Greek alphabet, π (piwas) is the sixteenth letter. In the English alphabet, p is also the sixteenth letter.^{d}
 The letter π is the first letter of the Greek word “periphery” and “perimeter.” The symbol π in mathematics represents the ratio of a circle’s circumference to its diameter. In other words, π is the number of times a circle’s diameter will fit around its circumference.^{a}
 Egyptologists and followers of mysticism have been fascinated for centuries by the fact that the Great Pyramid at Giza seems to approximate pi. The vertical height of the pyramid has the same relationship to the perimeter of its base as the radius of a circle has to its circumference.^{d}
 The first 144 digits of pi add up to 666 (which many scholars say is “the mark of the Beast”). And 144 = (6+6) x (6+6).^{d}
 If the circumference of the earth were calculated using π rounded to only the ninth decimal place, an error of no more than one quarter of an inch in 25,000 miles would result.^{i}
 In 1995, Hiroyoki Gotu memorized 42,195 places of pi and is considered the current pi champion. Some scholars speculate that Japanese is better suited than other languages for memorizing sequences of numbers.^{a}
 A mysterious 2008 crop circle in Britain shows a coded image representing the first 10 digits of pi.^{b}
 Ludolph van Ceulen (15401610) spent most of his life calculating the first 36 digits of pi (which were named the Ludolphine Number). According to legend, these numbers were engraved on his now lost tombstone.^{c}
 William Shanks (18121882) worked for years by hand to find the first 707 digits of pi. Unfortunately, he made a mistake after the 527th place and, consequently, the following digits were all wrong.^{c}



It took a Hitachi SR 8000 supercomputer over 400 hours to compute pi to 1.24 trillion digits 


 In 2002, a Japanese scientist found 1.24 trillion digits of pi using a powerful computer called the Hitachi SR 8000, breaking all previous records.^{e}
 Pi is the secret code in Alfred Hitchcock’s Torn Curtainand in The Net starring Sandra Bullock.^{d}
 Since there are 360 degrees in a circle and pi is intimately connected with the circle, some mathematicians were delighted to discover that the number 360 is at the 359th digit position of pi.^{d}
 Computing pi is a stress test for a computer—a kind of “digital cardiogram.”^{d}
 Umberto Eco’s famed book Foucault’s Pendulum associates the mysterious pendulum in the novel with the intrigue of pi.^{d}
 Pi has been studied by the human race for almost 4,000 years. By 2000 B.C., Babylonians established the constant circle ratio as 31/8 or 3.125. The ancient Egyptians arrived at a slightly different value of 31/7 or 3.143.^{a}
 One of the earliest known records of pi was written by an Egyptian scribe named Ahmes (c. 1650 B.C.) on what is now known as the Rhind Papyrus. He was off by less than 1% of the modern approximation of pi (3.141592).^{l}
 The Rhind Papyrus was the first attempt to calculate pi by “squaring the circle,” which is to measure the diameter of a circle by building a square inside the circle.^{l}
 The “squaring the circle” method of understanding pi has fascinated mathematicians because traditionally the circle represents the infinite, immeasurable, and even spiritual world while the square represents the manifest, measurable, and comprehensive world.^{e}
 In 1888, a Indiana country doctor named Edwin Goodwin claimed he had been “supernaturally taught” the exact measure of the circle and even had a bill proposed in the Indiana legislature that would copyright his mathematical findings. The bill never became law thanks to a mathematical professor in the legislature who pointed out that the method resulted in an incorrect value of pi.^{d}
 The first million decimal places of pi consist of 99,959 zeros, 99,758 1s, 100,026 2s, 100,229 3s, 100,230 4s, 100,359 5s, 99,548 6s, 99,800 7s, 99,985 8s, and 100,106 9s.^{a}



Albert Einstein was born on Pi Day (3/14/1879) 


 ”Pi Day” is celebrated on March 14 (which was chosen because it resembles 3.14). The official celebration begins at 1:59 p.m., to make an appropriate 3.14159 when combined with the date. Albert Einstein was born on Pi Day (3/14/1879) in Ulm Wurttemberg, Germany.^{d}
 The Bible alludes to pi in 1 Kings 7:23 where it describes the altar inside Solomon’s temple: “And he made a molten sea of ten cubits from brim to brim . . . and a line of thirty cubits did compass it round about.” These measurements procure the following equation: 333/106 = 3.141509.^{k}
 Pi was first rigorously calculated by one of the greatest mathematicians of the ancient world, Archimedes of Syracuse (287212 B.C.). Archimedes was so engrossed in his work that he did not notice that Roman soldiers had taken the Greek city of Syracuse. When a Roman soldier approached him, he yelled in Greek “Do not touch my circles!” The Roman soldier simply cut off his head and went on his business.^{f}
 A refined value of pi was obtained by the Chinese much earlier than in the West. The Chinese had two advantages over most of the world: they used decimal notations and they used a symbol for zero. European mathematicians would not use a symbolic zero until the late Middle Ages through contact with Indian and Arabic thinkers.^{f}
 AlKhwarizmi, who lived in Baghdad around A.D. 800, worked on a value of pi calculated to four digits: 3.1416. The term “algorithm” derives from his name, and his text Kitab alJabr walMuqabala (The Book of Completion Concerning Calculating by Transposition and Reduction) gives us the word “algebra” (from alJabr, which means “completion” or “restoration”).^{c}
 Ancient mathematicians tried to compute pi by inscribing polygons with more and more sides that would more closely approach the area of a circle. Archimedes used a 96sided polygon. Chinese mathematicians Liu Hui inscribed a 192sided polygon and then a 3,072sided polygon to calculate pi to 3.14159. Tsu Ch’ung and his son inscribed polygons with as many as 24,576 sides to calculate pi (the result had only an 8millionth of 1% difference from the now accepted value of pi).^{f}
 William Jones (16751749) introduced the symbol “π” in the 1706, and it was later popularized by Leonhard Euler (17071783) in 1737.^{c}
 The π symbol came into standard use in the 1700s, the Arabs invented the decimal system in A.D. 1000, and the equal sign (=) appeared in 1557.^{e}
 Before the π symbol was used, mathematicians would describe pi in roundabout ways such as “quantitas, in quam cum multipliectur diameter, proveniet circumferential,” which means “the quantity which, when the diameter is multiplied by it, yields the circumference.”^{c}



Leonardo da Vinci briefly worked on ”squaring the circle” or approximating pi 


 Leonardo da Vinci (14521519) and artist Albrecht Durer (14711528) both briefly worked on “squaring the circle,” or approximating pi.^{d}
 There are no occurrences of the sequence 123456 in the first million digits of pi—but of the eight 12345s that do occur, three are followed by another 5. The sequence 012345 occurs twice and, in both cases, it is followed by another 5.^{i}
 Some scholars claim that humans are programmed to find patterns in the world because it’s the only way we can give meaning to the world and ourselves. Hence, the obsessive search to find patterns in π.^{e}
 The father of calculus (meaning “pebble used in counting” from calx or “limestone”), Isaac Newton calculated pi to at least 16 decimal places.^{l}
 Pi is also referred to as the “circular constant,” “Archimedes’ constant,” or “Ludolph’s number.”^{d}
 In the seventeenth century, pi was freed from the circle and applied also to curves, such as arches and hypocycloids, when it was found that their areas could also be expressed in terms of pi. In the twentieth century, pi has been used in many areas, such as number theory, probability, and chaos theory.^{a}
 The first six digits of pi (314159) appear in order at least six times among the first 10 million decimal places of pi.^{i}
 Thirtynine decimal places of pi suffice for computing the circumference of a circle girding the known universe with an error no greater than the radius of a hydrogen atom.^{i}
 John Donne’s (15721631) poem “Upon the Translations of the Psalms by Sir Philip Sidney, and the Countess of Pembroke, His Sister” condemns attempts to find an exact value of pi, or to “square a circle,” which Donne views as an attempt to rationalize God:
Eternal God—for whom who ever dare
Seek new expressions, do the circle square,
And thrust into straight corners of poor wit
Thee, who art cornerless and infinite—^{k}
 Many mathematicians claim that it is more correct to say that a circle has an infinite number of corners than to view a circle as being cornerless.^{e}
 Plato (427348 B.C.) supposedly obtained for his day a fairly accurate value for pi: √2 + √3 = 3.146.^{a}
 A Web site titled “The PiSearch Page” finds a person’s birthday and other well known numbers in the digits of pi.^{j}
— Posted July 3, 2009
References
^{a} Arndt, Jörg and Christoph Haenel. 2001. Pi Unleashed. Trans. Catriona and David Lischka. New York, NY: SpringerVerlag Berlin Heidelberg.
^{b} “Baffling Crop Circles Equal Pi.” Metro.co.uk. June 18, 2008. Accessed: June 15, 2009.
^{c} Beckmann, Petr. 1971. A History of Pi. New York, NY: Golem Press.
^{d} Blatner, David. 1997. The Joy of Pi. New York, NY: Walker Publishing Company.
^{e} Brown, James Robert. 2008. Philosophy of Mathematics: A Contemporary Introduction to the World of Proofs and Pictures. 2nd ed. New York, NY: Routledge.
^{f} Maor, Eli. 1987. To Infinity and Beyond: A Cultural History of the Infinite. Princeton, NJ: Princeton University Press.
^{g} “Pi: Faith in Chaos.” IMDB.com. Accessed: June 15, 2009.
^{h} “Pi by Givenchy.” Basenotes.com. Accessed: June 14, 2009.
^{i} Pickover, Clifford A. Keys to Infinity. Denver, CO: John Wiley & Sons, Inc.
^{j} The PiSearch Page. Updated April 17, 2006. Accessed: June 15, 2009.
^{k} Tubbs, Robert. 2009. What Is a Number?: Mathematical Concepts and Their Origins. Baltimore, MD: The John Hopkins University Press.
^{l} Zebrowski, Ernest, Jr. 1999. A History of the Circle: Mathematical Reasoning and the Physical Universe. New Brunswick, NJ: Rutgers University Press. 