  What's Special About This Number? If you know a distinctive fact about a number not listed here, please e-mail me. primes graphs digits sums of powers bases combinatorics powers/polygonal Fibonacci geometry repdigits algebra perfect/amicable pandigital matrices divisors games/puzzles 0 is the additive identity . 1 is the multiplicative identity . 2 is the only even prime . 3 is the number of spatial dimensions we live in. 4 is the smallest number of colors sufficient to color all planar maps. 5 is the number of Platonic solids . 6 is the smallest perfect number . 7 is the smallest number of sides of a regular polygon that is not constructible by straightedge and compass. 8 is the largest cube in the Fibonacci sequence . 9 is the maximum number of cubes that are needed to sum to any positive integer . 10 is the base of our number system. 11 is the largest known multiplicative persistence . 12 is the smallest abundant number . 13 is the number of Archimedian solids . 17 is the number of wallpaper groups .

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Can You Solve This Geometry Problem For Singapore Students? Finding The Area Of A Claw. Sunday Puzzle – Mind Your Decisions This geometry problem was asked to students in Singapore. What is the area of the shaded region? The figure is composed of squares with side length 4 and quarter circles. Physics Simulations and Artwork Here is a 3D view of a hydrogren atom in the 4f state. The left image was made in C++ using a technique described by Krzysztof Marczak to make it volumetric like a cloud of smoke. The right image was made in Mathematica by adding 2D cross-sectional layers. The animations were made in POV-Ray using DF3 density files. The right animation shows what a "12o" orbital might look like. POV-Ray has a built-in internal function for the 3d orbital: // runtime: 4 seconds camera{location 16*z look_at 0} #declare P=function{internal(53)}; #declare P0=P(0,3,0,0); box{-8,8 pigment{rgbt t} hollow interior{media{emission 0.5 density{function{(P(x,y,z,0)-1.2)/(P0-1.2)} color_map{[0 rgb 0][1 rgb 1]}}}}} Links Atomic Orbital - time-dependant hydrogen atom simulation, by ?

Confessions of a Car Salesman — Edmunds.com Car Buying Articles Republished: 05/04/2009 (Original Date: 01/18/2001) Car Buying Learning Center What really goes on in the back rooms of car dealerships across America? Hammack Home This book is an introduction to the standard methods of proving mathematical theorems. It has been approved by the American Institute of Mathematics' Open Textbook Initiative. Also see the Mathematical Association of America Math DL review (of the 1st edition), and the Amazon reviews. Binary numeral system The binary or base-two numeral system is a representation for numbers that uses a radix of two. It was first described by Gottfried Leibniz, and is used by most modern computers because of its ease of implementation using digital electronics--early 20th century computers were based the on/off and true/false principles of Boolean algebra. Binary can be considered the most basic practical numeral system (the Unary system is simpler, but impractical for most computation). Representation