Arithmetic and Algebra

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What Is Arithmetic?
What Is Algebra?
Mental Calculations

  1. 17 rooks on an 8×8 chessboard

  2. 3-Colors Tower of Hanoi [Java]
  3. 3 glass puzzle [JavaScript]
  4. 3-Term Arithmetic Progression
  5. 4x4 coloring problem
  6. A 49th Degree Challenge
  7. A Clique of Acquaintances
  8. A Line in a Square Grid [Java]
  9. Abacus in Various Number Systems [Java]
  10. About numbers
  11. Achieve the Equilibrium [Flash]
  12. Addition
  13. Affirmative Action Problem [Java]
  14. Algorithm for Computing LCM [Java]
  15. The Aliquot Game [Java]
  16. Algebraic Structure of Complex Numbers
  17. Almost every integer has the digit 3 in it
  18. Almost Integers - Gaussian Integers
  19. Ambassadors at a Round Table [Java]
  20. An Application of Mental Arithmetic to Highway Safety
  21. An Arithmetic Magic Trick [Java]
  22. An Inequality for Grade 8
  23. An Inequality With an Infinite Series
  24. An Interesting Number
  25. Arithmetic-Geometric Means Inequality
  26. Arithmetic magic matrix [Java]
  27. Arithmetic Operations in Various Bases [Java]
  28. Arithmetic Paradoxes
  29. A simple integral
  30. Another simple integral
  31. Averages, Arithmetic and Harmonic Means [Java]
  32. Averages in a sequence
  33. Bachet's Magic Trick [Java]
  34. Banzhaf Power Index Calculator [Java]
  35. Barcode Encoding
  36. Barcode Magic [Java]
  37. Base Converter [JavaScript]
  38. Basic Rules of Counting
  39. Bayes' Theorem
  40. Beatty Sequences
  41. Bilateral Diagrams [Java]
  42. Binary Color Device [Java]
  43. Binary Euclid's Algorithm
  44. Binomial Distribution [Java]
  45. Binomial Theorem\
  46. Bisector of an imaginary angle may be real
  47. Boys and Girls Solving Problems
  48. Breaking Chocolate Bars [Java]
  49. Broken Calculator [Java]
  50. Byzantine Basketball
  51. Calculation of the Digits of pi by the Spigot Algorithm [Java]
  52. Cantor-Bernstein-Schroeder theorem
  53. Cardinal Numbers
  54. Cartesian Coordinate System [Java]
  55. Caterpillar [Flash]
  56. Cavalieri's Principle [Java]
  57. Chameleons of Three Colors
  58. Chinese Remainder Theorem
  59. Clifford Algebras
  60. Collatz Conjecture [Java]
  61. Coloring a Graph [Java]
  62. Combinatorial Proofs
  63. Committee Chairs
  64. Compare Fractions: Interactive Practice [Java]
  65. Comparing complex numbers
  66. Completing a Square and Quadratic Formula
  67. Complex Numbers: A Dynamic Tool [Java]
  68. Complex number to a complex power may be real
  69. Computer As a Magician [Java]
  70. Constructible Numbers
  71. Continued fractions
  72. Countability of Rational Numbers
  73. Counting: The Beginning of Mathematics [Java]
  74. Counting Chips On a Circle [Java]
  75. Counting Squares in a Square [Java]
  76. Counting Triangles [Java]
  77. Counting Triangles II [Java]
  78. Covering A Chessboard With Domino
  79. Cryptarithms [JavaScript, Frames]
  80. Cubic Formula [JavaScript]
  81. Cubics and Bézout's Theorem
  82. Derivatives without Limits
  83. Descartes' Rule of Signs
  84. Distance between the Orthocenter and Circumcenter
  85. Distance Between Strings [Java]
  86. Distance From a Point to a Straight Line [Java]
  87. Distributive Law [Java]
  88. Dividing Loot Fairly
  89. Divisibility and Modulo Arithmetic at IMO 2007
  90. Divisibility by 7
  91. Divisibility by 9 and 11
  92. Divisibility by 81
  93. Divisibility Criteria
  94. Divisibility by 7, 11, and 13
  95. Dollars in Pockets
  96. Dot Patterns and Sierpinski Gasket [Java]
  97. Dots and fractions [Java]
  98. Ducci Sequences [Java]
  99. EAN-13 Encoding [Java]
  100. Egyptian Multiplication [Java]
  101. Eigenvectors by Inspection
  102. Equations of the Staight Line [Java]
  103. Equivalence Relations
  104. Euclid's Algorithm
  105. Euclid's Algorithm: An Interactive Illustration [Java]
  106. Euclid's Game [Java]
  107. Euler’s formula for e
  108. Euler's Function and Congruence Theorem
  109. Evolution of Algebraic Symbolism
  110. Every composite number is the product of some factors and also the sum of the same numbers
  111. Extension of Euclid's Algorithm
  112. Factorials and division
  113. Factoring with the Factor Tree [Java]
  114. Fair Division: Method of Sealed Bids II [Java]
  115. Falsity implies anything
  116. Farey Series
  117. Fast Arithmetic Tips
  118. Fermat's Little Theorem
  119. Fibonacci's Quickies
  120. First Geometric Interpretation of Complex Numbers [Java]
  121. Five Methods of Apportionment [Java]
  122. Five Lattice Points [Java]
  123. Fleury's Algorithm and Euler's Paths and Cycles [Java]
  124. Flipping Items Simultaneously [Java]
  125. Flipping Items Simultaneously II [Java]
  126. Flipping pancakes [Java]
  127. Floor Function
  128. Formal Framework, an example
  129. Formal Systems - an Example
  130. Formula for Primes
  131. Four 3s
  132. Four 4s
  133. Four 5s
  134. Four Hinged Squares: using complex numbers
  135. Four Pegs That Form a Square
  136. Four Voting Methods [Java]
  137. Fraction Comparison [Java]
  138. Fractions on a Binary Tree
  139. Fractions on a Binary Tree II
  140. Frieze Patterns [Java]
  141. Fun with digits
  142. Function
  143. Fundamental Theorem of Algebra
  144. Funny Arithmetic [JavaScript]
  145. Gasoline Stations on a Circular Trek
  146. GCD and LCM via Factoring
  147. GCD(M, N) × LCM(M, N) = M × N [Java]
  148. Generalization That Solves the Problem
  149. Generating Functions
  150. Geometric Construction of Roots of Quadratic Equation [Java]
  151. Geometric view of the Sieve of Eratosthenes [Java]
  152. Gergonne Magic Trick [Java]
  153. Gödel's Incompleteness Theorem
  154. Graph and Roots of a Third Degree Polynomial [Java]
  155. Graph and Roots of Quadratic Polynomial [Java]
  156. Graph of a Polynomial [Java]
  157. Graph of a Polynomial Defined by Its Roots [Java]
  158. Group multiplication of permutations [Java]
  159. Guessing Two Consecutive Integers
  160. Finding Hamilton Paths and Circuits [Java]
  161. Harmonic Serires And Its Parts
  162. Heads and Tails [Java]
  163. Horner's Method [Java]
  164. Hour glass timing
  165. How to Ask an Embarrassing Question
  166. How to define a permutation? [Java]
  167. How to efficiently defend a castle
  168. Hyperintegers and Hyperreal Numbers
  169. Identical Twins Puzzle
  170. Identities in the Multiplication Table [Java]
  171. Implementation of Base Conversion
  172. Impossible Machine
  173. Importance of the Absolute Value
  174. Inclusion-Exclusion Principle
  175. Inequality 1/2·3/4·5/6· ... ·99/100 < 1/10
  176. Inequality (1 + 1-3)(1 + 2-3)(1 + 2-3)...(1 + n-3) < 3
  177. Inequality 1 + 2-2 + 3-2 + 4-2 + ... + n-2 < 2.
  178. Inequality from Math Magazine 2009
  179. Infinite Discent for x4 + y4 = z4
  180. Infinitesimals. Non-standard Analysis
  181. Infinitude of Primes
  182. Infinity As a Limit
  183. Inflection Points of Fourth Degree Polynomials [Java]
  184. Integer Iterations on a Circle [Java]
  185. Integer Iterations on a Circle III [Java]
  186. Integer roots of integers are irrational
  187. Integers and Rectangles [Java]
  188. Integers and Rectangles: a Proof by Induction [Java]
  189. Integers and Rectangles: Two Simple Proofs [Java]
  190. Interest Calculations [Java]
  191. ISBN Encoding [Java]
  192. Irrational number to an irrational power may be rational
  193. Is 0.999... = 1?
  194. It's All About Powers of 10
  195. Joachimsthal's Notations
  196. Jumping Isn't Everything [Java]
  197. Kaprekar's Iterations and Numbers [Java]
  198. Lagrange's identity, Proof
  199. Lagrange interpolation
  200. Langford and Skolem Sequences [Java]
  201. Latin Squares [Java]
  202. Lattice Multiplication [Java]
  203. Leibniz and Pascal Triangles [Java]
  204. Lewis Carroll's Game of Logic [Java]
  205. Light Bulbs in a Circle [Java]
  206. Lights Out [Java]
  207. Linear functions
  208. Linear Programming
  209. Listing All Combinations [Java]
  210. Listing all permutations [Java]
  211. Listing All Permutations: Johnson-Trotter Method [Java]
  212. Logistic Model applet [Java]
  213. Long Multiplication [Java]
  214. Long Runs of Composite Numbers
  215. Looking your best
  216. Loop or Halt [Java]
  217. Lucas' Theorem
  218. Magic in Square [Java]
  219. Make An Identity [Java]
  220. Make It All Zeros [Java]
  221. Market Day
  222. Marriage Theorem
  223. Marriage Problem, simulation [Java]
  224. Math Card Trick
  225. Math Lotto
  226. Math Telepathy [Java]
  227. Mathematical Induction
  228. Mathematical Proof
  229. Mathematicians Doze Off
  230. Matrix Groups
  231. Maximum Volume of a Cut Off Box [Java]
  232. Means [Java]
  233. Mediant Fractions
  234. Method of Markers II [Java]
  235. Minesweeper Theorem
  236. Mini Lights Out [Java]
  237. Minimax Principle [Java]
  238. Minimax Theorem [Java]
  239. Minumum Spanning Trees and Kruskal's Algorithm [Java]
  240. Modular Arithmetic [Java]
  241. Monotone Convergence Theorem
  242. Monotone Number Sequences [Java]
  243. Multiplication
  244. Napier Bones [Java]
  245. Napoleon's Relatives [Java]
  246. Nested Radicals
  247. Nested Subsets
  248. Newton's Method [Java]
  249. Nine Squares [Java]
  250. Number 8 Is Interesting
  251. Number Guessing Game [Java]
  252. Number sequences and Pigeonhole [Java]
  253. Number System With Base 36
  254. On the Games of Hex and Y
  255. One Dimensional Ants
  256. One Trigonometric Formula and Its Consequences
  257. Operations on Fractions [Java]
  258. Order. Well-ordered sets.
  259. Ordinal Numbers
  260. Outline Mathematics
  261. Parity counting [Java]
  262. Parrondo Paradox Via Simpson Paradox [Java]
  263. Party Acquaintances [Java]
  264. Peano axioms
  265. Peasant Multiplication [Java]
  266. Pennies in Boxes [Java]
  267. Percent
  268. Permutations
  269. Pigeonhole Principle
  270. Place Value [Java]
  271. Probability of Divisibility
  272. Problem 1 from the IMO 2009
  273. Problem A1, 69th Putnam Competition
  274. Problem A2, 69th Putnam Competition
  275. Problem of Divisibility by 5n
  276. Product of Diagonals in Regular N-gon
  277. Product Of Four Consecutive Integers
  278. Product of Simple Fractions [Java]
  279. Product of permutations [Java]
  280. Proizvolov's Identity [Java]
  281. Proofs Without Words [Java]
  282. Property of an
  283. Property of the Powers of 2 [Java]
  284. Yet Another Puzzle with Hats
  285. Puzzlist vs. Mathematician: A Practical Arithmetic Problem
  286. Pythagorean Triples [Java]
  287. Quasigroups and block designs from triangular grid [Java]
  288. Ramsey's Theorem
  289. Recombining Permutations [Java]
  290. Represent 4 with four digits
  291. Represent 6 with three digits
  292. Rectangle on a Chessboard [Java]
  293. Review of Arithmetic for Parents: A Book for Grownups about Children's Mathematics by R. Aharoni
  294. Rhind Papyrus
  295. Riemann Sphere and Möbius Transformation
  296. Riemann Sums - Function Integration [Java]
  297. Right Replacement [Java]
  298. Rolle's and Mean Value Theorems [Java]
  299. Round Robin Tournament
  300. Russell's Paradox
  301. Scheduling and Critical Path Algorithm [Java]
  302. Scrub Tile Puzzle [Java]
  303. Self-descriptive Strings [Java]
  304. Self-reference
  305. Seven Terms Periodic Sequence
  306. Shapley-Shubik Power Index [Java]
  307. Shapley-Shubik Power Index Calculator [Java]
  308. Shifting Digits and a Point of View
  309. Ship-Dock Theorem
  310. Sierpinski Gasket and Tower of Hanoi
  311. Sierpinski's Gasket and Dihedral Symmetry [Java]
  312. Sieve of Eratosthenes [Java]
  313. Sieve of Squares [Java]
  314. Σ2-n = Σn·2-n
  315. Signs and Sums in a Sequence [Java]
  316. Signs in a Matrix [Java]
  317. Simple Cellular Automaton [Java]
  318. Simple Graph Practice [Java]
  319. Simpson Paradox [Java]
  320. Sine of a Sum Formula, Proof Without Words
  321. Single formula to express any integer with digits 0-9 each used just once
  322. Six Balls, Two Weighings
  323. Slider Puzzles [Java]
  324. Solitaire in Two Colors [Java]
  325. Solve xx3 = 3
  326. Soriteses
  327. Soroban in Various Number Systems
  328. Sorting Algorithms
  329. Sperner's Theorem
  330. Splitting piles
  331. Square root of 2 is irrational
  332. Squares, Circles, and Triangles [Java]
  333. Steinhaus' Problem [Java]
  334. Step into the Elliptic Realm
  335. Stern-Brocot Tree
  336. Straight Tromino on a Chessboard [Java]
  337. Structure of Hyperreal Numbers
  338. Suan Pan in Various Number Systems [Java]
  339. Subtraction Game [Java]
  340. Sum without Adding
  341. Sums and Products [Java]
  342. Sums of powers of digits [Java]
  343. Superposition Principle
  344. Surreal Numbers
  345. Taking Games Seriously [Java]
  346. The ass and the mule [Java]
  347. The Size is in the Eyes of the Beholder
  348. Three 3s
  349. Three 4s
  350. Three 5s
  351. Tool for Constructing Orthogonal Latin Squares [Java]
  352. Three Dimensional Cross
  353. Tower of Hanoi, the Hard Way [Java]
  354. Transpositions
  355. Traveling Salesman Problem [Java]
  356. Triangular numbers that are also square
  357. Trilateral Diagrams [Java]
  358. Trinary Tree(s) underlying Primitive Pythagorean Triples
  359. Twenty five boys and twenty five girls around a table.
  360. Two Circles and a Limit [Java]
  361. Two Colors in Two Rows [Java]
  362. Two Men of Tibet [Java]
  363. Two Numbers Guessing Game [Java]
  364. Uncountability of the Reals - via a Game
  365. Universal Coloring [Java]
  366. Universal Product Code [Java]
  367. USA 1975 Problem 3
  368. Venn Diagrams
  369. Ways To Count
  370. Weierstrass Product Inequality
  371. Weighing 12 coins
  372. What, how, and the Web [Java]
  373. What Is Algorithm?
  374. What Is Fraction?
  375. What Is Infinity?
  376. What Is Limit?
  377. What is so natural about “natural logarithms”?
  378. WHEN THE COUNTING GETS TOUGH, THE TOUGH COUNT ON MATHEMATICS
  379. Where To Start? [Java]
  380. Why 1/3 + 1/4 = 7/12?
  381. Why 17?
  382. Wilson's Theorem
  383. With One 4
  384. Wolf and Rabbit [Flash]
  385. Word Problems [Java]
  386. Zeros and Nines [Java]

Copyright © 1996-2009 Alexander Bogomolny

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