@CutTheKnotMath

Freelance mathematician and educational web developer. I am a proud Israeli American, with love and respect for both countries.

 NJ, USA
cut-the-knot.org
Joined December 2009
  • Tweets14.9K
  • Following341
  • Followers20.5K
2.2KMedia
Probability in triangle #FigureThat #math #probability
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Lorian Saceanu's Inequality for All Triangles cut-the-knot.org/triangle/Lo… #FigureThat #math #geometry #inequality
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#FF for math @CutTheKnotMath @jamestanton @JohnAllenPaulos @GlobalMathProj @stevenstrogatz @monsoon0 @aussiemath @mathyawp @octonion @MathforLove @k8nowak @maanow @Derektionary @jamesgrime @peterrowlett @JohnDCook @mathematicsprof @Mathgarden @ilana_horn @MrHonner @wilderlab
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Here's a couple of solutions cut-the-knot.org/m/Probabili… xitter.cf/CutTheKnotMath/status/…
Alexander Bogomolny@CutTheKnotMath4 Jul 2018
Probability in triangle #FigureThat #math #probability
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Seeking problems with 4/7 probability being involved. E.g., Diminishing Hopes II #FigureThat #math #probability cut-the-knot.org/Probability…
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Every one can take part in this statistical research. Every one is invited xitter.cf/DegenRolf/status/10141…
Rolf Degen
@DegenRolf3 Jul 2018
You won't believe what great sh*t a psychologist managed to plant on a predatory journal. crimsonpublishers.com/pprs/p… h/t @maltoesermalte
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An Inequality from a Mongolian Exam cut-the-knot.org/m/Algebra/I… #FigureThat #math #algebra #inequality
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Let {x_k} be uniformly distributed on say, [-1,1] with the mean=0. Is that true that the variance is at least the square of the median? #FigureThat #math #probability
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Problem 2 from the Kurschak Contest 1970 #FigureThat #math #probability
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I was always suspicious of the "pseudo" part in pseudorandom xitter.cf/pomeranian99/status/10…
Clive Thompson
@pomeranian9930 Jun 2018
Russians engineer a way to beat slot machines — for which the casinos have no defense. Insanely interesting piece here by @brendankoerner: wired.com/2017/02/russians-e…
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Very elegant xitter.cf/jordancurve/status/101…
Josh Jordan
@jordancurve28 Jun 2018
Replying to @jordancurve
Simple way to determine if a year is a leap year: If the last two digits of the year are 00, throw them away and keep only the first two digits. Otherwise, keep only the last two digits. The year is a leap year if what you kept is divisible by 4.
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Dorin Marghidanu's Functional Equation cut-the-knot.org/m/Algebra/D… #FigureThat #math #algebra
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#FF for math @CutTheKnotMath @jamestanton @JohnAllenPaulos @GlobalMathProj @stevenstrogatz @monsoon0 @aussiemath @mathyawp @octonion @MathforLove @k8nowak @maanow @Derektionary @jamesgrime @peterrowlett @JohnDCook @mathematicsprof @Mathgarden @ilana_horn @MrHonner @wilderlab
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Alexander Bogomolny retweeted
James Tanton
@jamestanton30 Jun 2018
Oh! It's #ff! Add to this ... @republicofmath (of course!) @cbrownLmath @henryseg @margaretwerth @EulersNephew @maanow @timchartier @evelynjlamb @Dr_Kreisberg @NaturalMath @mikeandallie @MathWithMatthew @DavidKButlerUoA @alittlestats @nomad_penguin @aperiodical @NoCOMTC xitter.cf/republicofmath/status/…
Republic of Mathematics@republicofmath30 Jun 2018
#FF for math @CutTheKnotMath @jamestanton @JohnAllenPaulos @GlobalMathProj @stevenstrogatz @monsoon0 @aussiemath @mathyawp @octonion @MathforLove @k8nowak @maanow @Derektionary @jamesgrime @peterrowlett @JohnDCook @mathematicsprof @Mathgarden @ilana_horn @MrHonner @wilderlab
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I've nothing to say about that. Perhaps somebody will xitter.cf/TigerWhite44/status/10…
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Alexander Bogomolny retweeted
Sam Walters ☕️@SamuelGWalters29 Jun 2018
Replying to @CutTheKnotMath
It can be equivalently rephrased as saying that if a product of 2n integers is (-1)^n (n!)^2, then their sum is zero.
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Product of Integers That Add Up to 2018 cut-the-knot.org/m/Algebra/I… #FigureThat #math #algebra
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A problem from the early 1980s (Canada) #FigureThat #math #algebra #arithmetic
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Here's a couple of solutions cut-the-knot.org/m/Algebra/I…
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The discriminant of a quadratic polynomial with integer coefficients equals 23. What can be said about the roots of the polynomial. The more you say, the better. #FigureThat #math #algebra
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