 Percentage Increase/Decrease  Math Forum, Ask Dr. Math Common Question
A selection of answers to questions about percentage increase and decrease, such as "Why doesn't a decrease of 15%, followed by an increase of 15%, get you back to where you started?" and "If I increase an initial amount by P percent, by what percentage
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 Percent  David Giordano
For Win95/98/ME/NT4/2000/XP, or for Pocket PC/Windows CE: calculate the percentage of any number out of any number. Free trial download; shareware program.
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 Perfection  Greg Lobanov
This mobile game for iPhone and Android handheld devices presents convex and concave polygonal shapes for players to cut into the outlines indicated. Available directly from the iTunes app store and Google Play.
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 Perfect Numbers  MacTutor Math History Archives
Linked essay describing the work on perfect numbers from Pythagoras through Euclid, Nicomachus, the Arabs, Cataldi, Descartes, Mersenne, Fermat, Euler, Barlow, Catalan, Cole, and others; with other web sites and 20 references (books/articles).
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 Perfect Numbers  Math Forum, Ask Dr. Math FAQ
What is a perfect number? How many are there? How can you calculate a perfect number from a Mersenne prime?
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 Permadi.com  F. Permadi
Java and Flash applets: logic games, drawing and patternmaking programs, Conway's Life, and more arcadestyle offerings. Also includes tutorials in using Flash and a graphics gallery.
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 Permutations and Combinations  Math Forum, Ask Dr. Math FAQ
How to calculate all possible groupings of objects where order does  or doesn't  matter.
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 Personalized Programming Service Inc.
Educational software for teachers and students. Topical software in Math, English, Social Studies, and Science, as well as Quizmaker and Testmaker programs. Download demos and upgrades, browse the products, or order on site.
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 Perspective Drawing  Jan Garner
An examination of geometry in art: exercises in drawing, pictures and paintings in perspective on the Web (Albrecht Dürer, the Ancient City of Athens exhibit).
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 Peter Ash's Thoughts on Math and Education  Peter Ash
Musings on doing and teaching mathematics, book reviews, and math problems both elementary and advanced from the creator of Cambridge Math Learning. Blog posts, which date back to August of 2007, include "Very Proper Fractions"; "Physical Models for NonEuclidean
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 Peter Gustav Lejeune Dirichlet  Australian Mathematics Trust
A biography of the mathematician that discusses his theorem, introduction of the function notation y = f(x), boundary problems, minimization principle, and the Pigeonhole Principle.
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 Peter J. Lu  Department of Physics, Harvard University
Lu's mathematical and historical research has revealed new insights in medieval Islamic quasicrystalline tilings and the earliest machines, such as the one he suggests precisely interconverted the linear and rotational motion responsible for the distinctive
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 Peterson's Education Center
A leading provider of information on U.S.accredited educational institutions in the U.S. and abroad. Topics include: Summer Programs for Kids and Teens; Public Schools K12; Private Day and Boarding Schools; VocationalTechnical Schools; Undergraduate
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 Peter Winton's Radical Home Page
Math topics include puzzles, a gallery of fractals, and Visual Basic programs to download (count the grains of rice on a chessboard, or graph different curves).
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 Petits Textes sur l'éducation  Laurent Lafforgue
Essais écrit par le laureat de la medaille Fields 2002, incluent "De l'école et de ce qui fonde la valeur de la culture et du savoir" et "De la culture générale des futurs instituteurs et professeurs" et "Les mathématiques
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 Phenomenological Pizza (SMILE)  Robert Foote, Disney Magnet School
A lesson for the middle grades designed to teach students to calculate the area of a circle, find how many twotopping pizzas can be made using 14 toppings, and determine cost per square inch. From the Geometry and Measurement section of a collection
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 Phenomenological Probability (SMILE)  Robert Foote, Disney Magnet School
A lesson for grades 68 designed to find the difference between theoretical and experimental probability in three different experiments: rolling dice, using marbles and a spinner, and through a card trick. From the Probability and Statistics section of
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 The 'PhiNest'  Gary Meisner
This source for the golden section, golden mean, divine proportion, Fibonacci Series, and phi discusses phi "for neo'phi'tes"; credit cards; energy; geometry; history; life; the human hand; the human face; the human body; human beauty; development; the
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 Phi's Fascinating Figures  Ron Knott
More properties of the number Phi, its multiples and powers, continued fractions, formulae, and numerical relations between Phi and its powers.
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 Phi: That Golden Number  Mark Freitag, Univ. of Georgia
Phi can be found in many geometric shapes as an approximation of the Golden Ratio. A geometric figure commonly associated with Phi is the Golden Rectangle, which has sides A and B that are in proportion to the Golden Ratio. It has been said that the Golden
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 Photographic Polyhedron (Geometry and the Imagination)  Conway, Doyle, Gilman, Thurston; The Geometry Center
As you stand in one place and look around, up, and down, there is a sphere's worth of directions you can look. One way to record what you see would be to construct a big sphere, with the image painted on the inside surface. To see the world as viewed
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 PhotoMath  Martha Jean Barrett; Kodak
A project where students created their own mathematical board games for use with younger or less advanced students, for grades 48. Working in teams, advanced students covered seven math categories: whole numbers, decimals, fractions, measurement, geometry,
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 PhotoMath  microblink
"Smart camera calculator" apps that use a cell phone's builtin camera to read mathematical expressions in real time, then output stepbystep solutions.
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 Physics Forums
Discussions emphasize physics, but "PF" also includes an entire directory on mathematics: General Math; Calculus & Analysis; Differential Equations; Linear & Abstract Algebra; Topology & Geometry; Set Theory, Logic, Probability, and Statistics;
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 The Physics of Baseball  Alan Nathan
Read about the benefits (or not) of corked bats, the differences between aluminum and wood bats, the issues involved with characterizing the performance of bats from a physics point of view, and a description of the collision between a wooden bat and
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 Pi = 3.14159...  Math Forum, Ask Dr. Math FAQ
What is Pi? Who first used Pi? How do you find it? How many digits is it?
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 Pi Across America  University of Phoenix
Join the "Pi Pilot" for a "journey to one of humankind's most intriguing and celebrated numbers." Activities include "The Great Chain of Pi," "Taking Pi to Court," "Your Place in Pi," "Freehand Circle Drawing Competition," "Pi Party," and "Pi Bee." Scenario
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 Pi and Square Roots  Don Cohen (The Mathman)
Kohler (a 5thgrader) follows Archimedes. A graph and a program for iterating the square root of 10. Sample problems with some answers from Chapter 10 of Don Cohen's worksheet book.
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 Pi Approximation Day Greeting Cards  123Greetings
123Greetings  Send Free Electronic Greeting Cards to Friends and Families all over the World. There are no images available for Pi Approximation Day, but backgrounds and a variety of slogans are available, and you can write your own.
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 Pi: A Source Book  J. Borwein, SpringerVerlag
A complete history of pi, with resources for teachers for anything from special topic courses to individual talks and special student projects. The literature on pi included in this source book falls into three classes: a selection of the mathematical
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 Pick a Digit, Any Digit  Ivars Peterson (MathTrek)
One of the most amazing mathematical results of the last few years was the discovery of a surprisingly simple formula for computing digits of the number pi. Unlike previously known methods, this one allows you to calculate isolated digits  without computing
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 Pick a number from 1 to 10 ... for SCIENCE!  Alec Perkins
"When asked 'pick a number from 1 to 10,' people tend to pick certain numbers more than others, in particular 7 and 4 over the extremes...." Participate by choosing your own number; see bar graphs and line plots of data submitted thus far according to
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 Picking Winners  Ivars Peterson (MathTrek)
One of the attractive features of spectator sports is the uncertainty of the outcome. Even when one team is overwhelmingly favored to win, the underdog may still come through with a surprising victory. Nonetheless, the ability to pick winners can be of
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 Pico Firme Bago  Evan M. Fuchs
A Flashbased logic/deduction game, similar to Mastermind. Originally created as an online version of a game used in the author's 5th grade class.
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 Pi Day  Herte; Finley Middle School, Glen Cove, NY
Pi Day is March 14th, a day to celebrate mathematics in school, to allow students to have fun while investigating mathematics concepts and being creative and even a little silly. This page describes a number of Pi Day activities. You are invited to email
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 Pi Day: Making a Pi Necklace  Diana Funke
Diana Funke teaches mathematics at Davisville Middle School in North Kingstown, RI. Her students make a Pi necklace for Pi Day to reinforce the idea that some numbers never repeat or end. They assign a color to each digit (including 0) and then string
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 Pi Day  Math Forum, Teacher2Teacher FAQ
Answers to a frequently asked question: What activities can I use for Pi Day?
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 The PiDye TShirt Shop  Josh Cummings
Purchase from a variety of pi and other math tshirts, mugs, clocks, etc., including the famous MathSpeak tshirt.
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 Pieces 'n Creases: A Fun Guide to Origami  Herring, Long, Haeggquist, Jeremy; ThinkQuest Junior
Contents include the history of origami; uses and benefits; terms, symbols, and tips; origami and peace; poems about origami; activities, and resources for folding paper. An awardwinning entry from Vidor Middle School.
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 The PiFactory  David Whitfield
Revision notes, boardshots, and Excel worksheets to download, from when the author used to teach in North London. The PiFactory includes an opensource assessment suite, classroom resources, and concept maps. The PiFactory conveniently pulls together
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 PiNation.com  Hugh Bell
A site to "... just enjoy pi. Leave the math aside. Don't even think about the circumference of a circle." Create unique representations of the decimal expansion of pi with the PiArt Tool: choose the color for each digit, the number of decimal places,
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 The Pi Pages  Centre for Experimental and Constructive Mathematics (CECM)
"Pi is one of the few concepts in mathematics whose mention evokes a response of recognition and interest in those not concerned professionally with the subject. It has been a part of human culture and the educated imagination for more than twenty five
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 PiSearch
Search the first four billion binary digits of Pi for a string. Enter the string in hex (4 bit) or character (5 bit) format. Includes some statistics (probability of occurrence of characters, digits). Related links include articles and papers.
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 The Pi Song  Hester Lewellen
Pi Song audio and sheet music. This musical scale is aligned to the digits of pi.
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 PI Team Chess Game
A multiple player chess game. PI Team Chess builds strong problem solving,
critical thinking, math and teamwork skills. Site includes chess lesson plans, scholastic research on chess, and problem solving activities.
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 Pi Through the Ages  MacTutor Math History Archives
A history of pi: the Rhind papyrus (Egypt), Ptolemy, Tsu Ch'ung Chi, al'Khwarizmi, Al'Kashi, Viet, Romanus, Van Ceulen, Gregory, Shanks, Lambert, Euler, Buffon, and many more, with other Web sites and 30 references (books/articles).
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 The Pixel Calculator  METIP (Mathematics Experiences Through Image Processing) Project
The Pixel Calculator is intended primarily for use by students of ages 1217 in a variety of enrichment activities involving mathematics and digital image processing. It provides a good introduction for students to digital images by allowing students
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 PJ's Mathematical Gold Nuggets  Pam Strout; Bethel High School, Bethel, Connecticut
Links relating to K12 research topics in mathematics and mathematics teaching collected and usefully annotated by a mathematics teacher.
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 Place Value  Cut the Knot!, Alexander Bogomolny
Dictionary definitions of place value and what they lack; the emphasis on place value in the NCTM Standards; its importance in understanding our numeration system; how it arises from one of several possible representations of grouping in the counting
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 Place Value  Math Forum, Teacher2Teacher FAQ
Answers to a frequently asked question: How do I provide my students with practice on their place value skills?
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