Fun maths facts

122 entries

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• "Match-Stick" Geometry
  • Published in 1939
  • Added on 2020-12-20
• A combinatorial approach to sums of two squares and related problems
  • Published in 2002
  • Added on 2010-07-16
• A combinatorial theorem in plane geometry
  • Published in 1975
  • Added on 2015-02-23
• A Discrete and Bounded Envy-Free Cake Cutting Protocol for Any Number of Agents
  • Published in 2016
  • Added on 2016-10-13
• A Hamiltonian circuit for Rubik's Cube
  • Published in 2012
  • Added on 2012-09-04
• A number system with an irrational base
  • Published in 1957
  • Added on 2014-03-12
• A Prime-Representing Constant
  • Published in 2020
  • Added on 2020-11-06
• A Self-Referential Property of Zimin Words
  • Published in 2016
  • Added on 2021-03-31
• A simple mnemonic to compute sums of powers
  • Published in 2022
  • Added on 2022-04-24
• A unique pair of triangles
  • Published in 2018
  • Added on 2019-12-10
• A universal differential equation
  • Published in 1981
  • Added on 2019-05-09
• Amusing Permutation Representations of Group Extensions
  • Published in 2018
  • Added on 2019-01-01
• An example of a computable absolutely normal number
  • Published in 2002
  • Added on 2011-03-28
• An Infinite Set of Heron Triangles with Two Rational Medians
  • Published in 2013
  • Added on 2013-10-09
• An Interesting Serendipitous Real Number
  • Published in 2000
  • Added on 2020-09-21
• An Optimal Solution for the Muffin Problem
  • Published in 2019
  • Added on 2020-08-17
• Any Monotone Boolean Function Can Be Realized by Interlocked Polygons
  • Published in 2010
  • Added on 2018-01-08
• Are There More Finite Rings than Finite Groups?
  • Published in 2020
  • Added on 2021-01-06
• Bell-ringing methods as polyhedra
  • Published in 2015
  • Added on 2021-11-20
• Bells, Motels and Permutation Groups
  • Published in 2012
  • Added on 2014-12-17
• Best Laid Plans of Lions and Men
  • Published in 2017
  • Added on 2017-03-22
• Biologically Unavoidable Sequences
  • Published in 2012
  • Added on 2012-12-16
• Braids which can be plaited with their threads tied together at each end
  • Published in 1962
  • Added on 2021-02-12
• Brainfilling Curves - a Fractal Bestiary
  • Published in 2012
  • Added on 2019-05-09
• Brazilian Primes Which Are Also Sophie Germain Primes
  • Published in 2019
  • Added on 2019-03-13
• Can One Hear the Shape of a Drum?
  • Published in 1966
  • Added on 2011-01-12
• Check Digits
  • Published in 1999
  • Added on 2022-01-18
• Chords of an ellipse, Lucas polynomials, and cubic equations
  • Published in 2018
  • Added on 2019-06-30
• Convex Equipartitions: The Spicy Chicken Theorem
  • Published in 2013
  • Added on 2022-04-24
• Conway and Doyle Can Divide by Three, But I Can't
  • Published in 2023
  • Added on 2023-09-29
• Conway's doughnuts
  • Published in 2018
  • Added on 2018-11-04
• Conway's Rational Tangles
  • Published in 2012
  • Added on 2013-02-06
• Conway's Tiling Groups on JSTOR
  • Published in 1990
  • Added on 2020-04-15
• Cool irrational numbers and their rather cool rational approximations
  • Published in 2003
  • Added on 2011-10-13
• Denser Egyptian Fractions
  • Published in 1998
  • Added on 2015-07-23
• Descending Dungeons and Iterated Base-Changing
  • Published in 2006
  • Added on 2022-02-28
• Distant decimals of $π$
  • Published in 2017
  • Added on 2023-08-14
• Division by three
  • Published in 2006
  • Added on 2014-11-17
• Easy Proof of Three Recursive $π$-Algorithms -- Einfacher Beweis dreier rekursiver $π$-Algorithmen
  • Published in 2019
  • Added on 2022-02-25
• Efficient Algorithms for Zeckendorf Arithmetic
  • Published in 2012
  • Added on 2015-02-16
• Embedding countable groups in 2-generator groups
  • Published in 1993
  • Added on 2013-02-19
• Envelopes are solving machines for quadratics and cubics and certain polynomials of arbitrary degree
  • Published in 2020
  • Added on 2021-01-06
• Equilibrium solution to the lowest unique positive integer game
  • Published in 2010
  • Added on 2012-06-22
• Euclidean traveller in hyperbolic worlds
  • Published in 2022
  • Added on 2022-09-09
• Every natural number is the sum of forty-nine palindromes
  • Published in 2015
  • Added on 2016-12-17
• Every positive integer is a sum of three palindromes
  • Published in 2016
  • Added on 2017-06-21
• Fibonacci determinants-a combinatorial approach
  • Published in 2007
  • Added on 2012-02-08
• Filling space with hypercubes of two sizes -- The pythagorean tiling in higher dimensions
  • Published in 2022
  • Added on 2022-05-13
• Four Pages Are Indeed Necessary for Planar Graphs
  • Published in 2020
  • Added on 2020-04-19
• Fractal Sequences
  • Published in 1999
  • Added on 2019-08-21
• Gergonne's Card Trick, Positional Notation, and Radix Sort
  • Published in 2017
  • Added on 2020-05-30
• Goldbug Variations
  • Published in 2005
  • Added on 2020-06-12
• Gödel's incompleteness theorem
  • Published in 1994
  • Added on 2011-06-01
• Gödel's Second Incompleteness Theorem Explained in Words of One Syllable
  • Published in 1994
  • Added on 2011-09-24
• Half of a coin: negative probabilities
  • Published in 2005
  • Added on 2013-07-17
• Hilbert 13: Are there any genuine continuous multivariate real-valued functions?
  • Published in 2021
  • Added on 2021-02-02
• How big a table do you need for your jigsaw puzzle?
  • Published in 2023
  • Added on 2024-01-15
• How to hear the shape of a billiard table
  • Published in 2018
  • Added on 2018-06-27
• Indigenous perspectives in maths: Understanding Gurruṯu
  • Published in 2020
  • Added on 2020-06-08
• Infinitude of Primes Using Formal Language Theory
  • Published in 2020
  • Added on 2020-05-25
• Irrationality From The Book
  • Published in 2009
  • Added on 2014-12-01
• Knots and links in spatial graphs
  • Published in 1983
  • Added on 2020-04-12
• Laying train tracks
  • Published in 2011
  • Added on 2011-12-03
• Least Significant Non-Zero Digit of n!
  • Published in 2000
  • Added on 2020-10-22
• Maclaurin Integration: A Weapon Against Infamous Integrals
  • Published in 2022
  • Added on 2022-10-08
• Mathematics applied to dressmaking
  • Published in 1994
  • Added on 2018-11-29
• Maximum overhang
  • Published in 2007
  • Added on 2021-03-15
• On a curious property of 3435
  • Published in 2009
  • Added on 2011-02-02
• On a problem of Störmer
  • Published in 1964
  • Added on 2013-07-11
• On Kaprekar's Junction Numbers
  • Published in 2021
  • Added on 2022-01-10
• On Some two way Classifications of Integers
  • Published in 1959
  • Added on 2020-03-13
• On sphere-filling ropes
  • Published in 2010
  • Added on 2012-10-29
• On subsets with intersections of even cardinality
  • Published in 1969
  • Added on 2016-11-01
• On the Cookie Monster Problem
  • Published in 2013
  • Added on 2016-05-19
• On The Euclidean Algorithm: Rhythm Without Recursion
  • Published in 2022
  • Added on 2022-07-08
• On the Existence of Ordinary Triangles
  • Published in 2017
  • Added on 2017-02-06
• On the interval containing at least one prime number
  • Published in 1952
  • Added on 2016-11-14
• One parameter is always enough
  • Published in 2018
  • Added on 2018-06-06
• Orange Peels and Fresnel Integrals
  • Published in 2012
  • Added on 2012-02-15
• Palindromes in Different Bases: A Conjecture of J. Ernest Wilkins
  • Published in 2009
  • Added on 2019-09-14
• Planar graph is on fire
  • Published in 2015
  • Added on 2015-12-02
• Planar Hypohamiltonian Graphs on 40 Vertices
  • Published in 2013
  • Added on 2019-05-09
• Plane-filling curves on all uniform grids
  • Published in 2016
  • Added on 2020-09-21
• Playing pool with $\pi$ (the number $\pi$ from a billiard point of view)
  • Published in 2003
  • Added on 2013-11-14
• Prime Number Races
  • Published in 2004
  • Added on 2018-11-12
• Prime numbers in certain arithmetic progressions
  • Published in 2001
  • Added on 2016-05-07
• Proof without Words: Fair Allocation of a Pizza
  • Published in 1994
  • Added on 2018-06-26
• Pythagorean Triples, Complex Numbers, Abelian Groups and Prime Numbers
  • Published in 2021
  • Added on 2021-02-12
• Rational Polynomials That Take Integer Values at the Fibonacci Numbers
  • Published in 2016
  • Added on 2016-08-02
• Rules for Folding Polyminoes from One Level to Two Levels
  • Published in 2017
  • Added on 2017-01-16
• Searching for generalized binary number systems
  • Published in 2017
  • Added on 2016-08-22
• Seven Trees in One
  • Published in 1994
  • Added on 2018-11-26
• Six Ways to Sum a Series
  • Published in 1994
  • Added on 2013-06-10
• Solving Triangular Peg Solitaire
  • Published in 2007
  • Added on 2014-11-10
• Some Doubly Exponential Sequences
  • Published in 1970
  • Added on 2020-07-13
• Stuttering look and say sequences and a challenger to Conway's most complicated algebraic number from the silliest source
  • Published in 2022
  • Added on 2022-07-08
• The Amazing $3^n$ Theorem and its even more Amazing Proof [Discovered by Xavier G. Viennot and his École Bordelaise gang]
  • Published in 2012
  • Added on 2021-03-15
• The cocked hat
  • Published in 2020
  • Added on 2021-03-23
• The Collatz Fractal
  • Published in 2012
  • Added on 2012-01-15
• The Instructor's Guide to Real Induction
  • Published in 2012
  • Added on 2019-03-02
• The largest small hexagon
  • Published in 1975
  • Added on 2018-09-22
• The mate-in-n problem of infinite chess is decidable
  • Published in 2012
  • Added on 2012-03-28
• The no-three-in-line problem on a torus
  • Published in 2012
  • Added on 2019-12-10
• The Packing Chromatic Number of the Infinite Square Grid is 15
  • Published in 2023
  • Added on 2023-01-26
• The Sine of a Single Degree
  • Published in 2017
  • Added on 2024-01-15
• The Strange and Surprising Saga of the Somos Sequences
  • Published in 1991
  • Added on 2013-10-09
• The Strong Law of Small Numbers
  • Published in 1988
  • Added on 2022-07-05
• The Takagi Function and Its Properties
  • Published in 2011
  • Added on 2019-03-04
• The Ubiquitous Pi
  • Published in 2013
  • Added on 2013-06-11
• The Ubiquitous Thue-Morse Sequence
  • Published in 2006
  • Added on 2013-10-21
• The wobbly garden table
  • Published in 2001
  • Added on 2012-06-17
• Tiling with arbitrary tiles
  • Published in 2015
  • Added on 2022-02-23
• Topology Explains Why Automobile Sunshades Fold Oddly
  • Published in 2012
  • Added on 2012-05-23
• Two short proofs of the Perfect Forest Theorem
  • Published in 2016
  • Added on 2016-12-18
• Unbounded spigot algorithms for the digits of pi
  • Published in 2006
  • Added on 2010-01-05
• Wallpaper Functions
  • Published in 2002
  • Added on 2023-06-20
• When are Multiples of Polygonal Numbers again Polygonal Numbers?
  • Published in 2018
  • Added on 2018-06-25
• When Can You Tile an Integer Rectangle with Integer Squares?
  • Published in 2023
  • Added on 2023-10-09
• Word calculus in the fundamental group of the Menger curve
  • Published in 2013
  • Added on 2020-05-02
• World's shortest explanation of Gödel's theorem
  • Published in 2009
  • Added on 2020-10-16
• Yet another Proof of an old Hat
  • Published in 2021
  • Added on 2021-11-20
• Yet Another Single Law for Lattices
  • Published in 2003
  • Added on 2019-03-02