 Rounding Numbers  Math Forum, Ask Dr. Math FAQ
How do you round a number to the nearest tenth (10th), hundredth (100th), thousandth (1000th), etc.?
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 Rounding Seconds  NASA Lewis Learning Technologies Project
Erv ran the 110 meter high hurdles in 13.27 seconds. His teammate, Willie, ran the same race in 12.91 seconds. Rounded to the nearest tenth of a second, how much faster was Willie's time? A detailed answer is provided. From NASA's 9th Grade Math Proficiency
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 Rouse Ball's Fallacy  Interactive Mathematics Miscellany and Puzzles, Alexander Bogomolny
A famous fallacy by Rouse Ball now implemented in Java. A proof that an obtuse angle is right. How can that be?
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 Route ICS (formerly DeweyWeb): Interactive Communications and Simulations  Univ. of Michigan
An effort to link distant schools and expand the classroom experience: using telecommunications and computer conferencing, students can spend part of every school day in a "global classroom." Crossroads: The Route 12 Project is a grassroots attempt to
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 Row Your Boat  Ivars Peterson (MathTrek)
Although a rowing shell with eight rowers is much larger than one with a single rower, all shells have roughly the same proportions (at least for the surface area over which the shell makes contact with water). Data from 2000meter world and Olympic championship
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 Roxanne Eckenrode's Storefront  Lulu.com  Free SelfPublishing  Roxanne Eckenrode
Selfpublished math worksheets. Several are free. They are downloadable and printable; correct answers will spell out a message or fill in a puzzle.
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 Royal Tyrrell Museum of Palaeontology
Virtual site for a science museum named for Joseph Tyrrell, who in 1884 travelled to what is now Alberta, Canada to study coal deposits and found the first dinosaur remains ("Albertosaurus") in the Drumheller area. The museum's mandate is to collect,
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 RSA Laboratories' Frequently Asked Questions About Today's Cryptography  RSA Laboratories
Cryptography FAQs organized into eight chapters: introduction, cryptography, techniques in cryptography, applications of cryptography, cryptography in the real world, laws concerning cryptography, miscellaneous topic, and further reading. With appendices
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 R. S. Schaeffer  Randy S. Schaeffer, Math & Computer Science, Kutztown University of Pennsylvania
Schaeffer teaches a course called "Methods of Teaching Secondary Mathematics." Download the lessons created by his students that call on Geometer's Sketchpad, graphing calculators, and Microsoft Excel. Lesson topics address parallel lines, box and whisker
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 Rubik's Cube Information  Michael Reid
All about Rubik's Cube  even a mailing list. Site contents include: the Nederlandse Kubus Club; Rubik's cube pages on the Web; Cube books; Sources of cubelike puzzles; the author's notes, including an optimal cube solver; other Cube solutions on the
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 Rubik's Cube Java Applet  Michael Schubart
To twist the cube, press the mouse button over a cubelet face that belongs to the slice you want to move. Keeping the button pressed, drag the mouse in the desired direction; then release the button. Moving the whole cube is done in the same way  just
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 Rubik's Games  Androsoft
Dedicated to the first PC CDROM game from Erno Rubik, Rubik's Games contains 5 subgames: Rubik's Classic, Cover Up, Paint War, Rubik's Playground and ZigThrough. Download the Rubik's Games Web Site Plugin plugin or a demo of the Rubik's Game CDROM.
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 Rubik's Online  Rubik/Seven Towns
The official online site for the Rubik's cube. Play with the cube and other Rubik's games and puzzles online; find information on where to buy Rubik's products; use the forum to exchange views, opinions, comments, suggestions and anecdotes related to
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 Rubix Corner  Duane Cash
The site includes information regarding the Duane Cash Cube Collection now featured at Hessport's Rubikshop in their "collectibles" section. New puzzles include the Rubik's Triamese, Fusion, Fusion+, SpeedFusion, 5x3, and 4x3 Cubes, which give those interested
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 Rudi Mathematici  Rudy d'Alembert, Alice Riddle, and Piotr R. Silverbrahms
Matematica, giochi matematici, problemi, indovinelli e farneticazioni. Soprattutto una rivista, RM contiene Il Compleanno, Problemi del Mese, Bungee Jumpers, Soluzioni e Note, Quick & Dirty, Pagina 46, Paraphernalia Mathematica, Allegati ed Eventuali,
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 Rungs and Vineyards  Paul Kunkel
Investigations of two interesting visual effects seen from a moving automobile. It includes two interactive perspective drawings, and a discussion of the
cylindrical and planar projections used to create them.
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 Runiter Company  Saeid Nourian
Demo or purchase software that plots math functions in 3D or in or grid sheets, rotates them, and manipulates them in realtime: Smart Math Calculator, Graphing Calculator, A&G Grapher (algebra and geometry), Statistics Problem Solver, and Calculus Problem
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 Russian Peasant Multiplication  Math Forum, Ask Dr. Math FAQ
What is Russian peasant multiplication? How do I use it? Why does it work? How is the Russian peasant algorithm connected to binary numbers?
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 Russian School of Mathematics
An afterschool math enrichment program "based on the best practices of advanced math schools in Russia and Europe and adapted to the US educational environment." Cofounded in 1997 by Inessa Rifkin and Irina Khavinson — who recall that, in the
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 Rymar  Rymar Applications
"Helping with math homework and concepts one app at a time." The Cramer's Rule app finds the solution of a system of equations with 2 or 3 unknown variables, and also reveals — via the "Help" button — all of the intermediate determinants.
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 Sabermetrics  The Baseball Archive
"The search for objective knowledge about baseball." Read a primer of Bill James' findings, or David Grabiner's manifesto on Sabermetrics. Studies address minor league equivalencies ("Are minor league stats a good precictor of major league performance?"),
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 Sabernomics: Economic Thinking about Baseball  JohnCharles Bradbury
A blog on the economics in, and of, the game of baseball. Original tools and studies includes salary estimators, research on age and hitting and pitching, antitrust and Major League Baseball, attendance and winning, Barry Bonds and walks, competition
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 SABER  The World Bank Group
An open data tool that provides comparative data on education policies around the world. The Systems Approach for Better Education Results (SABER) web tool aims to help countries collect and analyze information on their education policies, benchmark themselves
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 SABES: System for Adult Basic Education Support  Massachusetts Department of Elementary & Secondary Education
SABES promotes high quality adult basic education services through training, support, and resources that improve the skills and knowledge of practitioners and strengthen programs. SABES strives to achieve this mission by: providing staff development that
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 SACNAS Biography Project  Society for the Advancement of Chicanos and Native Americans in Science
Highlights of the life stories and professional contributions of Native American, Chicano and Latino scientists, mathematicians, and engineers. The Project was created so that K12 students could see themselves reflected in the stories of the lives that
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 Sacramento Area Math Help and Tutoring  Just Math Learning Centers
Just Math provides math help, tutoring and SAT prep for Sacramento area children through college students. Skills training in elementary math, algebra, geometry, and calculus.
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 Sacred Geometry  Bruce Rawles
"In nature, we find patterns, designs and structures from the most minuscule particles, to expressions of life discernible by human eyes, to the greater cosmos. These inevitably follow geometrical archetypes, which reveal to us the nature of each form
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 Sacred Geometry Discovery  J. Vincent Beall
The Platonic solids are used to organize theosophical terms. The five regular solids are the basis for a threedimensional map of the Kabbalistic Tree of Life.
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 Sage: Open Source Mathematics Software  William Stein, University of Washington
An open source mathematics program designed to do everything from map a 12dimensional object to calculate rainfall patterns under global warminganything Maple, Matlab, or Mathematica would do. This free software reveals how it performs its calculationsso
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 Salinon: From Archimedes' Book of Lemmas  Interactive Mathematics Miscellany and Puzzles, Alexander Bogomolny
A description of Archimedes' application of propositions from the second book of Euclid's Elements to mathematical proofs. An interactive Java exploration is provided.
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 Saltire Software
Mathematical technology for industry and education. Saltire Software's core technologies are constraintbased interactive geometry systems, symbolic algebra, and optimization, with products for mechanical engineering, mathematics education and layout
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 SAM Learning  SAM Learning Ltd.
U.K. exam revision (review) for A Levels (age 1618), GCSEs (age 1416) and SATs (KS3, age 1114; KS2, age 711; KS1, age 57). Draganddrop exercises and online tests of math knowledge.
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 Sam Loyd Official Site  The Sam Loyd Company
This site is dedicated to introducing Sam Loyd and his puzzles to a whole new generation. Loyd was a famous puzzle inventor in the 1800s, till his death in 1911. Puzzles with answers, descriptions of famous puzzles for sale, FAQs and other information.
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 SAMMO  Sinclair, Nathalie; Murphy, Pat; et al.
Tools for exploring, creating, and doing mathematics. Sinclair's Java applets let middle school students explore appealing mathematical situations not normally included in school curricula while using fractions, ratios, decimal numbers, and other concepts
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 Sampling and the Census  Ivars Peterson  Science News Online
Despite strong support from statisticians, the Census Bureau's plan to increase the use of sampling in the next census has met resistance in Congress.
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 Samuel Arbesman
Research and writings by the author of The HalfLife of Facts. As an applied mathematician and network scientist, Arbesman's delves into the science of science, nature of productivity and prosocial behavior within cities, the structure and function of
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 San Antonio Technology in Education Coalition (SATEC)  Paul Tisdel, Project Coordinator
A mathematics curriculum project funded by the U.S. Dept. of Education to create mathematics lessons that seamlessly and appropriately integrate technology into instruction. Download PDF files on functions in algebra; technologies used include Vernier
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 San Diego Math Tutor  Juan Castaneda
Math Tutor in San Diego. Offering test preparation and help with Algebra, Calculus, Geometry, Trigonometry, and Statistics.
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 San Diego Tutor
A San Diegobased inhome tutoring company, San Diego Tutor offers a Scholarship program for clients who can't afford high school math and science tutoring.
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 The Sands of Time  Troy Jones
The author uses ridges in piles of salt to model geometric concepts. This page features an article (PDF format), PowerPoint presentation, Geometer's Sketchpad file, and textbook reference for a classroom exploration of such concepts.
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 Sangaku  Hiroshi Kotera
Click on the map of Japan to see photographs of sangaku  Euclidean geometry theorems rendered as colored drawings on wooden tablets, and hung in shrines or temples  dating to the Edo period (16031867). Also, learn how to use counting rods, called
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 Sangaku, Japanese Temple Geometry  Tony Rothman, Princeton University
For centuries in Buddhist and Shinto shrines, Japanese have hung wooden tablets containing mathematical problems. Read PDF or PS downloads of a tutorial on the inversion method for solving Sangaku, or of the article "Japanese Temple Geometry," which first
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 Sangaku: Reflections on the Phenomenon  Interactive Mathematics Miscellany and Puzzles, Alexander Bogomolny
A collection of sangaku problems with Java simulations and complete solutions, preceded by an introductory article that promotes an unorthodox view point on the wonderful phenomenon of Temple Geometry.
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 Sarah Glaz
Teaching, research, books, and articles by the algebraist, ring theorist, and poet. See, in particular, the math poems of undergraduate students and Glaz's own poetry, which includes "Mathematical Modeling," "A Pantoum for the Power of Theorems," "I am
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 sarahmarie belcastro's home page  SarahMarie Belcastro
From one of the authors of Making Mathematics with Needlework: "I seem to have become a topological graph theorist while I wasn't looking. I am also interested in convex and combinatorial geometry, algebraic geometry, topology, algebra, the geometry of
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 The SAT: Aptitude or Demographics?  Glenn Elert
A paper discussing the SAT's validity, coachability, biases, and implications, especially with respect to race and socioeconomic status.
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 SAT Free Math Practice  Roland Mfondoum
Download free SAT prep math worksheets, take autoscoring quizzes online, and watch videos on algebra and functions, factorization, polynomial expression expansion, linear equations and inequalities, quadratic equation solving, numbers and operations,
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 Satlink  Missouri School Boards Association (MSBA)
A monthly national magazine that serves as a guide to educational satellite teleconferences and programs concerning most K12 subjects, including many math areas. These programs can be a source for new information or an additional resource for current
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 SAT Math Pro  Colleen King
Interactive video lessons, timed quizzes, and other instruction for SAT math preparation, categorized into assess, practice, and strategies.
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 SAT Math Section Overview  SATPeer
Overviews of the geometry and algebra found on the SAT. SATPeer also posts articles of standardized testtaking strategies, review guides, and tools.
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