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 |