Apr 20 
The Circle of the Orthocenters 
Apr 20 
A 2Variable Optimization From a China Competition 
Apr 19 
Probability of Majorization II 
Apr 19 
Inheriting Inequality 
Apr 17 
Training Bicyclists on a Mountain Road 
Apr 17 
A Simple Integral of a Peculiar Function 
Apr 17 
Pythagorean Theorem by Contradiction 
Apr 16 
A Few Variants of a Popular Inequality And a Generalization 
Apr 15 
Two Balls of the Same Color 
Apr 15 
Probability in Scoring 
Apr 14 
Two Balls Out Of Four 
Apr 14 
Cyclic Inequality In Three Variables from the 2018 Romanian Olympiad, Grade 9 
Apr 13 
Cyclic Inequality in Four Variables By D. Sitaru 
Apr 13 
A Question about the Median 
Apr 12 
A Fancy Sum from the APMO 2000, Problem 1 
Apr 12 
Lights on a Christmas Tree 
Apr 12 
Cyclic Inequality In Three Variables From Vietnam by Rearrangement 
Apr 11 
A Quick Proof of cos(pi/7)cos(2.pi/7)cos(3.pi/7)=1/8 
Apr 11 
A Search for heads and Its Consequences  After Miller And Sanjurjo 
Apr 11 
Cyclic Inequality in Four Variables 
Apr 11 
An Inequality in a Convex Quadrilateral 
Apr 10 
A Simple Inequality with Many Variables 
Apr 10 
Cyclic Inequality In Three Variables From Kvant 
Apr 9 
Problem 8 from the Spring 2018 Mathcounts 
Apr 9 
Two Colors  Three Points  Any Triangle 
Apr 8 
Problem 25 from the Spring 2018 Mathcounts 
Apr 7 
A Problem of Three Liars 
Apr 7 
A Problem of Two Liars 
Apr 7 
Looking for the Prime Decomposition 
Apr 6 
Distributing Balls of Two Colors in Two Bags 
Apr 5 
An Inequality in a Nonobtuse Triangle 
Apr 5 
A Broken Line in 3D 
Apr 5 
Artificially Unintelligent 
Apr 4 
Galton's Paradox 
Apr 4 
An Inequality with Cubic Roots 
Apr 3 
Factorial Divisibility 
Apr 2 
Playing with Balls of Two Colors 
Apr 2 
An Inequality with Central Binomials 
Apr 2 
An Appearance of a 306090 Triangle 
Apr 1 
A Remote Decimal Digit

Mar 29 
Alexandru Lupas' Property of the Incenter 
Mar 29 
Taking Turns to Toss a Die 
Mar 28 
A Missing Digit 
Mar 27 
Two 6s in a Row 
Mar 27 
Second Pair of Twin Inequalities: Twin 2 
Mar 27 
Second Pair of Twin Inequalities: Twin 1 
Mar 26 
Planting Trees in a Row 
Mar 25 
Probability of Average 
Mar 24 
Equilateral Triangle In a Pretty Diagram 
Mar 24 
Yet Another Simple Integral 
Mar 24 
Red Faces of a Cube 
Mar 23 
Butterfly in Complex Numbers 
Mar 23 
Coloring Squares, Adding up Numbers 
Mar 23 
In Praise of Odds 
Mar 22 
Taking Chances with Your Medicine 
Mar 21 
Dan Sitaru's Cyclic Inequality In Three Variables with Constraints V 
Mar 21 
Probability of the Second Marble 
Mar 20 
On Gauss' Shoulders 
Mar 19 
A Little More of Algebra for an Inequality, A Little Less of Calculus for a Generalization 
Mar 19 
Right Strategy for a Weaker Player 
Mar 18 
Planar Sets with Integer Distances between Points 
Mar 18 
Random Numbers And Obtuse Triangle 
Mar 17 
A Little of Algebra for an Inequality, A Little of Calculus for a Generalization 
Mar 16 
Probability of First Digit in Product 
Mar 15 
Walking Randomly  How Far? 
Mar 14 
Trigonometric Identity for the Pi Day 
Mar 13 
A Property of Nagel Cevians 
Mar 12 
Gambling in a Company 
Mar 10 
Losing Socks Over a Year 
Mar 9 
Probability of First Digits in a Sequence of Powers 
Mar 7 
Probability of No TwoTail Runs 
Mar 6 
Crossing Bridge in Crowds 
Mar 6 
Diagonals in a Polygon Parallel to Sides 
Mar 5 
An Inequality with Five Variables, Only Three Cyclic 
Mar 4 
Two Coins: One Fair, one Biased 
Mar 4 
Probability in the World Series 
Mar 3 
Illustrated Sum of Cubes  All in a Plane 
Mar 3 
Golden Ratio in YinYang 
Mar 3 
An Estimate for the Roots of Quadratic Equation 
Mar 2 
A Cyclic Inequality by Seyran Ibrahimov 
Mar 2 
An Exercise in Complex Numbers: Problem 4217 from Crux 
Mar 1 
Clumps on a One Lane Road 
Feb 28 
A Straightedge Construction of the Midpoint of a Chord Common to Two Circles 
Feb 27 
Golden Ratio in Isosceles Triangle II 
Feb 26 
Hung Nguyen Viet's Inequality with a Constraint 
Feb 26 
Expected Number of Happy Passengers 
Feb 24 
A Curious Property of Numbers 3 and 5 
Feb 24 
A Three Group Split 
Feb 23 
Probability in Dart Throwing 
Feb 23 
Snake Permutations And Their Number 
Feb 23 
An Inequality in Triangle form the 1996 APMO 
Feb 22 
Kunihiko Chikaya's Inequality with a Constraint 
Feb 22 
Expectation of the Largest Number 
Feb 21 
Cute Exercise by Dorin Marghidanu 
Feb 21 
Arithmetic of Pie Sharing 
Feb 21 
Dan Sitaru's Inequality with a Double Integral 
Feb 20 
Circle Center by Paperfolding 
Feb 20 
Waiting for All Six Outcomes 
Feb 19 
Golden Ratio in Circles 
Feb 19 
Uniqueness of Number 5 
Feb 18 
Luca Moroni's Problem In Equilateral Triangle 
Feb 18 
A Triangle in a Rhombus with a 60 Degrees Angle 
Feb 17 
Acting As a Team I 
Feb 16 
Two in a Row 
Feb 15 
Golden Ratio in Isosceles Triangle 
Feb 15 
A Property of Angle Bisectors 
Feb 15 
Probability of a Random Inequality 
Feb 14 
Probability of a Meet in an Elimination Tournament 
Feb 14 
Golden Ratio in Two Squares, Or, Perhaps in Three 
Feb 14 
Thanos Kalogerakis's Problem in Circle and Square 
Feb 13 
Playing with Integers and Limits 
Feb 13 
Golden Ratio in Equilateral Triangle on the Shoulders of George Odom 
Feb 13 
A Modified Sangaku 
Feb 11 
Converting Temperature From $C^{\circ}$ to $F^{\circ}$ 
Feb 11 
A Problem in a Configuration of Three Squares 
Feb 10 
Golden Ratio in Square 
Feb 9 
Triangle on a Rectangular Hyperbola 
Feb 9 
Euler Line Through a Vertex 
Feb 9 
Ji Chen's Inequality 
Feb 9 
Functional Inequality from Vietnam 
Feb 8 
Matching Socks in Dark Room 
Feb 8 
Guessing Hat Numbers 
Feb 6 
Inequality in Convex Quadrilateral 
Feb 5 
Solving a Peculiar Third Degree Equation 
Feb 5 
Stars in Array 
Feb 3 
Equal And Perpendicular Segments in a Square 
Feb 1 
Expectation of Interval Length on Circle 
Feb 1 
Waiting to Exceed 1 
Feb 1 
An Angle Inequality in Triangle with Perpendicular Medians 
Feb 1 
The Triangle of the Medians 
Jan 30 
Waiting for a Larger Number 
Jan 30 
Elegance in Integers by Dorin Marghidanu 
Jan 30 
Hadamard's Determinant Inequalities and Applications II 
Jan 30 
A Trigonometric Inequality with Ordered Triple of Variables 
Jan 29 
An Inequality with Two Triples of Variables II 
Jan 25 
Two Equilateral Triangles on Sides of a Square 
Jan 25 
Hadamard's Determinant Inequalities and Applications I 
Jan 25 
Random Sum 
Jan 24 
Number of Wire Loops 
Jan 24 
Probability of Random Lines Crossing 
Jan 24 
Shelving an Encyclopaedia 
Jan 23 
Tony Foster's Integer Powers in Pascal's Triangle 
Jan 22 
A Triangle Problem from Caucasus 
Jan 22 
The Most Likely Position 
Jan 20 
Volume Inequality in Tetrahedron 
Jan 20 
An Isoperimetric Problem in Quadrilateral 
Jan 18 
Dan Sitaru's Cyclic Inequality in Three Variables VIII 
Jan 17 
The Expected Number of Fixed Points 
Jan 16 
Choosing the Largest Random Number 
Jan 16 
Golden Ratio in Square And Circles 
Jan 15 
Pythagorean Theorem by Stretching 
Jan 15 
Quadrilateral Inscribed into Parallelogram 
Jan 14 
Dan Sitaru's Cyclic Inequality in Three Variables VII 
Jan 14 
Probability of an Odd Number of Sixes 
Jan 14 
To Bet Or Not To Bet 
Jan 14 
Simple Nameless Inequality 
Jan 14 
Dorin Marghidanu's Sums and Products 
Jan 13 
Three Complex Numbers Satisfy Fermat's Identity For Prime Powers 
Jan 13 
Dropping Numbers into a 3x3 Square 
Jan 12 
Sam Walters' Four Questions 
Jan 12 
Piecewise Carpets in Parallelogram 
Jan 11 
Why Can't They Be All Different? 
Jan 11 
6th European Mathematical Cup (2017), Junior Problem 4 
Jan 8 
Metamorphosis of a Quadratic Function 
Jan 7 
Flat Probabilities on a Sphere 
Jan 6 
A Welcome Problem for the Year 2018 
Jan 6 
A Farewell Problem for the Year 2017 
Jan 6 
An Inequality Involving Arithmetic And Geometric Means 
Jan 5 
The Marriage Problem 
Jan 4 
An Extension of a Sangaku with Touching Circles 
Jan 4 
The Coffee Shop Game 
Jan 2 
An Inequality with Two Triples of Variables 
Jan 1 
Flat Probabilities on a Sphere 