March 14, written 3-14 in the USA date format, is an unofficial celebration for Pi Day derived from the common three-digit approximation for the number π: 3.14. It is usually celebrated at 1:59 PM (in recognition of the six-digit approximation: 3.14159). Some, using a twenty-four-hour clock rather than a twelve hour clock, say that 1:59 PM is actually 13:59 and celebrate it at 1:59 AM or 3:09 PM (15:09) instead. Parties have been held by the mathematics departments of ...

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Pi Day, Pi Day - Pi Day, Pi Day - Pi Approximation Day, Pi Day - Notes

Read more here: » Pi Day: Encyclopedia II - Pi Day - Pi Day

The mathematical constant π is a real number which may be defined as the ratio of a circle's circumference (Greek περιφέρεια, periphery) to its diameter in Euclidean geometry, and which is in common use in mathematics, physics, and engineering. The name of the Greek letter π is pi (pronounced pie in English), and this spelling can be used in typographical contexts where the Greek letter is not available. π is also known as Archimedes' constant (not to be confused with Archime ...

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• Pi - Properties
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• Pi - Geometry
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• Pi - Continued fractions
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• Pi - Dynamical systems and ergodic theory
• Pi - Physics
• Pi - Probability and statistics
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• Pi - Numerical approximations of π
• Pi - Miscellaneous formulae
• Pi - Less accurate approximations
• Pi - Open questions
• Pi - The nature of π
• Pi - Fictional references
• Pi - π culture

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Due to the transcendental nature of π, there are no closed expressions for the number in terms of algebraic numbers and functions. Therefore numerical calculations must use approximations of π. For many purposes, 3.14 or 22/7 is close enough, although engineers often use 3.1416 (5 significant figures) or 3.14159 (6 significant figures) for more accuracy. The approximations 22/7 and 355/113, with 3 and 7 significant figures respectively, are obtained from the simple continued fraction expansion of π. [The approximation 355/113 is the very best one that may exp ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture, Pi - Memorizing Pi

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Pi - Geometry. π appears in many formulae in geometry involving circles and spheres. (All of these are a consequence of the first one, as the area of a circle can be written as A = ∫(2πr)dr ("sum of annuli of infinitesimal width"), and others concern a surface or solid of revolution.) Also, the angle measure of 180° (degrees) is equal to π radians. ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture

Read more here: » Pi: Encyclopedia II - Pi - Formulae involving π

The most pressing open question about π is whether it is a normal number -- whether any digit block occurs in the expansion of π just as often as one would statistically expect if the digits had been produced completely "randomly", and that this is true in every base, not just base 10. Current knowledge on this point is very weak; e.g., it is not even known which of the digits 0,…,9 occur infinitely ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture, Pi - Memorizing Pi

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This is the list of observances recognized in the United States and no more than two other independent countries. Annual observances in the United States - Days. January 13 - Stephen Foster Memorial Day February 1 - National Freedom Day [1] March 14 - Pi Day April 13 - Thomas Jefferson's birthday May 1 - Law Day [2] May 1 - Loyalty Day [3] 1st Thursday in May - National Day of Prayer [4] 2nd Sunday in May - Mother's Day [5] 3rd S ...

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• Annual observances in the United States - Days
• Annual observances in the United States - Weeks
• Annual observances in the United States - Months

Read more here: » Annual observances in the United States: Encyclopedia - Annual observances in the United States

March 14 (3/14 in US date format) marks Pi Day which is celebrated by many lovers of π. On July 22, Pi Approximation Day is celebrated (22/7 - in European date format - is a popular approximation of π). 355/113 (~3.1415929) is sometimes jokingly referred to as "not π, but an incredible simulation!" Singer Kate Bush's recently released album "Aerial" contains a song titled "π," in which she sings π to over one hundred decimal places. Fans have discovered that she got some of them wrong[1], however, and actually misses twenty-two numbers. Fans are ca ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture, Pi - Memorizing Pi

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Darwin Day is the anniversary of the birthday of Charles Darwin on February 12, 1809. Darwin provided the first coherent theory of evolution by means of natural selection and so the name is used by a set of loosely-associated events, usually organized locally to take place on or about Darwin's birthday, whose aim is to acquaint the public with the theory of evolution by natural selection and its importance to biology. The first event using the name Darwin Day appears to be one organized by The Humanist Community of Palo ...

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Ever since computers have calculated π to billions of decimal places, memorizing π has become a popular hobby for many people. The current world record is 83431 decimal places, and was set by a Japanese mental health counsellor named Akira Haraguchi, who is currently 59 years of age.[2] Before Haraguchi accomplished this on July 2, 2005, the world record was 42195, which was set by Hiroyuki Goto. See here, a website listing many people who have ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture, Pi - Memorizing Pi

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The word holiday has related but different meanings in English-speaking countries. Based on the words holy and day -, holidays originally represented special religious days. The word has evolved in general usage to mean any special day. In most of the English-speaking world a holiday is also a period spent away from home or business in travel or recreation (e.g. "I'm going on holiday to Mallorca next week"), the North American equivalent being "vacation". However, some Canadians (especially those of English or Irish decent) will use both the terms vacation and holiday interchangeably when referr ...

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In non-Euclidean geometry the sum of the angles of a triangle may be more or less than π radians, and the ratio of a circle's circumference to its diameter may also differ from π. This does not change the definition of π, but it does affect many formulae in which π appears. So, in particular, π is not affected by the shape of the universe; it is not a physical constant but a mathematical constant defined independently of any physical measurements. Nonetheless, it occurs often in physics. For example, consider Coulomb ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture, Pi - Memorizing Pi

Read more here: » Pi: Encyclopedia II - Pi - The nature of π

Main article: History of Pi. The value of π has been known in some form since antiquity. As early as the 20th century BC, Babylonian mathematicians were using π=25/8, which is within 0.5% of the exact value. It is sometimes claimed that the Bible states that π=3, based on a passage in 1 Kings 7:23 giving measurements for a round basin. Rabbi Nehemiah explained this by the diameter being from outside to outside while the circumference was the inner brim; but it may suffice that the measurements are given in round numbers. (Also, the basin ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture, Pi - Memorizing Pi

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Due to the transcendental nature of π, there are no closed expressions for the number in terms of algebraic numbers and functions. Therefore numerical calculations must use approximations of π. For many purposes, 3.14 or 22/7 is close enough, although engineers often use 3.1416 (5 significant figures) or 3.14159 (6 significant figures) for more accuracy. The approximations 22/7 and 355/113, with 3 and 7 significant figures respectively, are obtaine ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture

Read more here: » Pi: Encyclopedia II - Pi - Numerical approximations of π

Main article: History of Pi. π has been known in some form since antiquity. References to measurements of a circular basin in the Bible appears to give a corresponding value of 3 for π: "And he made a molten sea, ten cubits from the one brim to the other: it was round all about, and his height was five cubits: and a line of thirty cubits did compass it round about." — 1 Kings 7:23; KJV. Nehemiah, a late antique Jewish rabbi and mathematician explained this apparent lack of precision in π, by considering the thicknes ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture

Read more here: » Pi: Encyclopedia II - Pi - History of π

π is an irrational number; that is, it cannot be written as the ratio of two integers, as was proven in 1761 by Johann Heinrich Lambert. π is also transcendental, as was proven by Ferdinand von Lindemann in 1882. This means that there is no polynomial with rational coefficients of which π is a root. An important consequence of the transcendence of π is the fact that it is not constructible. Because the coordinates of all points that can be constructed with ruler and compass are constructible numbers, it is impossible to square the circle, that is, it is impossible to construct, using ruler and compass alone, a square whose area is equ ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture

Read more here: » Pi: Encyclopedia II - Pi - Properties

The most pressing open question about π is whether it is a normal number -- whether any digit block occurs in the expansion of π just as often as one would statistically expect if the digits had been produced completely "randomly". This must be true in any base, not just in base 10. Current knowledge in this direction is very weak; e.g., it is not even known which of the digits 0,…,9 occur infinitely ...

See also:

Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture

Read more here: » Pi: Encyclopedia II - Pi - Open questions

π is an irrational number; that is, it cannot be written as the ratio of two integers, as was proven in 1761 by Johann Heinrich Lambert. π is also transcendental, as was proven by Ferdinand von Lindemann in 1882. This means that there is no polynomial with rational coefficients of which π is a root. An important consequence of the transcendence of π is the fact that it is not constructible. Because the coordinates of all points that can be constructed with ruler and compass are constructible numbers, it is impossible to square the circle, that is, it is impossible to construct, using ruler and compass alone, a square whose area is equ ...

See also:

Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture, Pi - Memorizing Pi

Read more here: » Pi: Encyclopedia II - Pi - Properties

There is an entire field of humorous yet serious study that involves the use of mnemonic techniques to remember the digits of π, which is known as piphilology. See Pi mnemonics for examples. March 14 (3/14 in US date format) marks Pi Day which is celebrated by many lovers of π. On July 22, Pi Approximation Day is celebrated (22/7 - in European date format - is a popular approximation of π). In the early hours of Saturday 2 July 2005, a Japanese mental health counsellor, Akira Haraguchi, 59, managed to recite π's first 83,431 decimal places from memory, thus breaki ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture

Read more here: » Pi: Encyclopedia II - Pi - π culture

Pi - Geometry. π appears in many formulae in geometry involving circles and spheres. (All of these are a consequence of the first one, as the area of a circle can be written as A = ∫(2πr)dr ("sum of annuli of infinitesimal width"), and others concern a surface or solid of revolution.) Also, the angle measure of 180° (degrees) is equal to π radians. ...

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Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture, Pi - Memorizing Pi

Read more here: » Pi: Encyclopedia II - Pi - Formulae involving π

In non-Euclidean geometry the sum of the angles of a triangle may be more or less than π radians, and the ratio of a circle's circumference to its diameter may also differ from π. This does not change the definition of π, but it does affect many formulae in which π appears. So, in particular, π is not affected by the shape of the universe; it is not a physical constant but a mathematical constant defined independently of any physical measurements. Nonetheless, it occurs often in physics. For example, consi ...

See also:

Pi, Pi - Properties, Pi - Formulae involving π, Pi - Geometry, Pi - Analysis, Pi - Continued fractions, Pi - Number theory, Pi - Dynamical systems and ergodic theory, Pi - Physics, Pi - Probability and statistics, Pi - History of π, Pi - Numerical approximations of π, Pi - Miscellaneous formulae, Pi - Less accurate approximations, Pi - Open questions, Pi - The nature of π, Pi - Fictional references, Pi - π culture

Read more here: » Pi: Encyclopedia II - Pi - The nature of π