| July 6 |
Lorian Saceanu's Inequality for All Triangles |
| July 5 |
Probability in Triangle |
| July 4 |
Diminishing Hopes II |
| July 3 |
An Inequality from a Mongolian Exam |
| July 1 |
Probability of Successive Integers |
| June 30 |
Dorin Marghidanu's Functional Equation |
| June 29 |
Product of Integers that Add Up to 2018 |
| June 28 |
An Integer Root of a Polynomial with Integer Coefficients |
| June 27 |
A Problem form the Short List of the 2018 JBMO |
| June 25 |
A Problem of Divisibility by 17 from the 1894 Eotvos Competition |
| June 23 |
An Inequality in Triangle for Side Lengths, Cycled in Two Ways |
| June 21 |
A Triangle out of Three Broken Sticks |
| June 19 |
Probability of Doubles |
| June 18 |
A Coin Tossing Surprise I |
| June 17 |
Fair Duel |
| June 15 |
Is a Sum a Prime Number? |
| June 15 |
A Moscow Olympiad Question with Two Inequalities |
| June 14 |
Lucky Times at a Moscow Math Olympiad |
| June 12 |
Averages of Terms in Increasing Sequence |
| June 12 |
An Inequality in Triangle with Radicals, Semiperimeter, Incenter and Inradius |
| June 11 |
An Equation in Factorials |
| June 10 |
Folding and Cutting a Square |
| June 6 |
Getting from A to B via C |
| June 6 |
Two Constraints, One Inequality by Qing Song |
| June 5 |
Lorian Saceanu's Sides And Angles Inequality |
| June 4 |
Probability of No Distinct Positive Roots |
| June 4 |
Rolling Defective Die |
| June 3 |
Dorin Marghidanu's Inequality with Powers and Reciprocals |
| June 2 |
An Inequality for the Tangent to the Incircle |
| June 1 |
Two Dice Repetition |
| May 29 |
Lucky Contest Winners |
| May 28 |
Random Clock Hands |
| May 27 |
Randomly Placed Letters in Envelopes |
| May 26 |
Leo Giugiuc's Cyclic Inequality in Square Roots |
| May 25 |
Probability of Equal Areas on a Chessboard |
| May 25 |
Points in a Semicircle |
| May 24 |
Point between Two Roads |
| May 22 |
How Long Will It Last? |
| May 21 |
Leo Giugiuc's Cyclic Inequality with a Constraint |
| May 18 |
An Incidental Sum of 24 |
| May 16 |
Check for Negative Roots |
| May 16 |
Mehmet Sahin's Identity in Triangle |
| May 15 |
Emptying a Big Number of Boxes |
| May 14 |
A True Algebraic-Geometric Inequality |
| May 14 |
The Shortest Distance in a Circular Segment |
| May 14 |
Lorian Saceanu's Inequality with Many Variables |
| May 13 |
Seven Integers That Add Up to 100 |
| May 13 |
A Cyclic Inequality in Three Variables XXVI |
| May 12 |
Counting Coins and Their Values |
| May 12 |
An Inequality with Two Variables from Awesome Math |
| May 11 |
Fixed Point of a Family of Parabolas |
| May 10 |
Expectation of Pairings |
| May 9 |
Minimum of Cotangents from Saint Petersburg |
| May 9 |
Leo Giugiuc and Vasile Cirtoaje's Cyclic Inequality |
| May 9 |
Vasile Cirtoaje's Cyclic Inequality with Three Variables |
| May 8 |
Probability of Having 5 in the Numerator |
| May 7 |
Find the Maximum and Minimum of a Function |
| May 6 |
Waiting for a Train |
| May 5 |
Probability of Equilateral Triangle |
| May 4 |
Lorian Saceanu's Cyclic Inequalities with Three Variables |
| May 4 |
Integer Sequence with Given Statistical Parameters |
| May 4 |
Thanos Kalogerakis' Collinearity in Triangle |
| May 3 |
Dan Sitaru's Inequality with Radicals and Cosines |
| May 3 |
Asymmetric Propeller of Squares II |
| May 2 |
An Inequality in Triangle with Radicals, Semiperimeter and Inradius |
| May 2 |
Asymmetric Propeller of Squares |
| May 1 |
Dan Sitaru's Cyclic Inequality in Three Variables IX |
| Apr 30 |
An Identity in Bicentric Isosceles Trapezoid |
| Apr 26 |
Random Arithmetic Progressions |
| Apr 25 |
Average Number of Runs in a Sequence of Random Numbers |
| Apr 24 |
Two Varsity Divisions |
| Apr 24 |
Labeling Subsets |
| Apr 23 |
Bubbling of Sorts |
| Apr 21 |
Equilateral Triangle from Three Centroids |
| Apr 21 |
Cutting a Cube into Smaller Ones |
| Apr 20 |
The Circle of the Orthocenters |
| Apr 20 |
A 2-Variable 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 30-60-90 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 Two-Tail 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 Yin-Yang |
| 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 |
