| July 2 |
Structure of Hyperreal Numbers |
| June 29 |
One Dimensional Ants |
| June 19 |
What Is Demagoguery? |
| June 17 |
Hyperintegers and Hyperreal Numbers |
| June 9 |
Models and Metamathematics |
| June 5 |
Fibonacci's Quickies |
| June 1 |
May the Product of Planes Be a Sphere? |
| May 31 |
Dollars in Pockets |
| May 31 |
One Trigonometric Formula and Its Consequences |
| May 29 |
Bimedians in a Regular Tetrahedron |
| May 29 |
Two Parallels in a Triangle and One More |
| May 28 |
Clifford Algebras |
| May 27 |
A better solution to a difficult sangaku problem |
| May 27 |
A Restored Sangaku |
| May 26 |
Probability of Divisibility |
| May 26 |
Product of Simple Fractions |
| May 26 |
IMO 2007, Problem 2, solution by Vo Duc Dien |
| May 25 |
Sum of Squares in Equilateral Triangle |
| May 21 |
Bisection of Yin and Yang |
| May 19 |
Counting Squares in a Square |
| May 15 |
A Review of Pythagoras' Revenge by Arturo Sangalli |
| May 15 |
A Line in a Square Grid |
| May 14 |
Two Color Coloring of the Plane |
| May 11 |
Two Sangaku with Equal Incircles |
| May 8 |
Formal Systems - an Example |
| May 5 |
GCD(M, N) × LCM(M, N) = M × N |
| May 4 |
What Is Fraction? |
| May 3 |
Fraction Comparison |
| Apr 29 |
Gödel's Incompleteness Theorem |
| Apr 29 |
Theories and Proofs |
| Apr 28 |
Morley's Theorem, Proof by R. Smyth |
| Apr 27 |
Napoleon's Theorem via Two Rotations |
| Apr 26 |
Morley's theorem, Proof by Nolan L Aljaddou |
| Apr 23 |
Möbius' Strip |
| Apr 11 |
Intuitive Probability |
| Apr 10 |
Dawson's Kayles |
| Apr 10 |
Dawson's Chess |
| Apr 3 |
On the Games of Hex and Y |
| Apr 3 |
Infinitesimals. Non-standard Analysis |
| Apr 2 |
Infinitude of Primes - A Topological Proof without Topology |
| Apr 1 |
A Triangle of Antreas Hatzipolakis |
| Mar 31 |
Six Concyclic Points II |
| Mar 30 |
Solutions to the Third Millennium Olympiad |
| Mar 29 |
Grebe: from Ladies' Diary to Carroll's Pillow |
| Mar 25 |
A Parallelogram in Triangle |
| Mar 24 |
Is Every Trapezoid Parallelogram? |
| Mar 23 |
On the Difference of Areas |
| Mar 21 |
Matrix Groups |
| Mar 18 |
Number 8 Is Interesting |
| Mar 14 |
Iterations on a Circle Through Three Points |
| Mar 14 |
Pigeonhole in Clubs |
| Mar 8 |
Angles in a Cube III |
| Mar 7 |
Squares in Circles |
| Mar 7 |
Circles with Tangent Diameters |
| Mar 3 |
Four Hinged Squares: using complex numbers |
| Feb 28 |
Minesweeper Theorem |
| Feb 20 |
Proof 19 of irrationality of √2 |
| Feb 17 |
Angles in a Cube I |
| Feb 17 |
Angles in a Cube II |
| Feb 12 |
Pascal: Necessary and Sufficient |
| Feb 6 |
Butterflies in Hyperbola |
| Feb 4 |
Problem 5 from IMO 2004 |
| Feb 4 |
Morley's theorem, a proof by B. Stonebridge |
| Feb 2 |
Urquhart's theorem - From Leningrad Mathematical Olympiad |
| Jan 31 |
An Inequality for Grade 8 |
| Jan 30 |
Proof 81 of the Pythagorean theorem |
| Jan 29 |
Morley's theorem, B. Bollobás' proof |
| Jan 27 |
Stereographic Projection |
| Jan 23 |
Problem 1 from IMO 2006 |
| Jan 20 |
Irrationality of √2, Proof #14 and Proof #8'' |
| Jan 18 |
Tangent Circles and an Isosceles Triangle II |
| Jan 17 |
Problem 4 from IMO 2007, Solution VII |
| Jan 16 |
Three Pyramids are Better Than Two |
| Jan 15 |
Orthocenter and Three Equal Circles |
| Jan 14 |
Equal Circles, Medial Triangle and Orthocenter |
| Jan 13 |
Cut the Cube |
| Jan 13 |
Cut the Cylinder |
| Jan 11 |
Cut the Cone |
| Jan 8 |
Between Major and Minor Circles |
| Jan 6 |
An Interesting Example of Angle Trisection by Paperfolding |
| Jan 5 |
Fundamental Theorem of Algebra: A Simple Complex Analysis Proof and An Advanced Calculus Proof |
| Jan 3 |
Irrationality of √2, Proof #17, Proof #18, Proof #19 |
| Jan 2 |
Construction of Conics from Pascal's Theorem |
| Jan 1 |
Irrationality of √2, Proof #16 |
