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"published_at": "2012-06-01T14:03:39+00:00" }, { "id": "01a0c54b-e04e-732b-8598-a93ec21a58d2", "title": "An interesting multivariable calculus example", "url": "https://divisbyzero.com/2012/04/18/an-interesting-multivariable-calculus-example/", "published_at": "2012-04-19T02:52:58+00:00" }, { "id": "01a0c54b-e04e-732b-8598-a93ec2b7de32", "title": "Parametric curve project for multivariable calculus", "url": "https://divisbyzero.com/2012/02/21/parametric-curve-project-for-multivariable-calculus/", "published_at": "2012-02-22T03:27:50+00:00" }, { "id": "01a0c554-2ef3-70b9-a09a-c9583eb67839", "title": "Cantor set applet", "url": "https://divisbyzero.com/2011/10/28/cantor-set-applet/", "published_at": "2011-10-29T02:32:56+00:00" }, { "id": "01a0c554-2ef3-70b9-a09a-c9583fa62717", "title": "Applet to illustrate the epsilon-delta definition of limit", "url": "https://divisbyzero.com/2011/10/28/applet-to-illustrate-the-epsilon-delta-definition-of-limit/", "published_at": "2011-10-29T02:21:14+00:00" }, { "id": "01a0c554-2ef3-70b9-a09a-c9583fd704fc", "title": "The danger of false positives", "url": "https://divisbyzero.com/2011/10/07/the-danger-of-false-positives/", "published_at": "2011-10-07T18:54:32+00:00" }, { "id": "01a0c554-2ef3-70b9-a09a-c9583fe39fdb", "title": "A neat probability rule-of-thumb", "url": "https://divisbyzero.com/2011/09/14/a-neat-probability-rule-of-thumb/", "published_at": "2011-09-15T02:25:00+00:00" }, { "id": "01a0c554-2ef3-70b9-a09a-c95840d86121", "title": "Advice for new college students", "url": "https://divisbyzero.com/2011/08/30/advice-for-new-college-students/", "published_at": "2011-08-30T15:17:21+00:00" }, { "id": "01a0c554-2ef3-70b9-a09a-c958418393a7", "title": "A quick guide to LaTeX", "url": "https://divisbyzero.com/2011/08/17/a-quick-guide-to-latex/", "published_at": "2011-08-17T20:27:38+00:00" }, { "id": "01a0c554-2ef3-70b9-a09a-c958423a7aa0", "title": "Highlights from MathFest 2011", "url": "https://divisbyzero.com/2011/08/12/highlights-from-mathfest-2011/", "published_at": "2011-08-13T03:47:34+00:00" }, { "id": "01a0c554-2ef3-70b9-a09a-c9584254eb88", "title": "The Japanese theorem for nonconvex polygons", "url": "https://divisbyzero.com/2011/06/22/japanese-theorem-for-nonconvex-polygons/", "published_at": "2011-06-22T18:18:39+00:00" }, { "id": "01a0c554-2ef3-70b9-a09a-c958434c74cd", "title": "Some LaTeX odds and ends", "url": "https://divisbyzero.com/2011/06/08/some-latex-odds-and-ends/", "published_at": "2011-06-09T01:10:24+00:00" }, { "id": "01a0c554-2ef3-70b9-a09a-c958442f7dc4", "title": "Extreme examples and counterexamples", "url": "https://divisbyzero.com/2011/06/05/extreme-example-and-counterexamples/", "published_at": "2011-06-06T03:49:36+00:00" }, { "id": "01a0c55c-954d-723d-8d02-402a4fa56172", "title": "Hankel on Diophantus", "url": "https://divisbyzero.com/2011/05/31/hankel-on-diophantus/", "published_at": "2011-05-31T21:10:20+00:00" }, { "id": "01a0c55c-954d-723d-8d02-402a4ffcd49d", "title": "What shape are the golden arches?", "url": "https://divisbyzero.com/2011/05/11/what-shape-are-the-golden-arches/", "published_at": "2011-05-11T20:14:48+00:00" }, { "id": "01a0c55c-954d-723d-8d02-402a50ac8feb", "title": "Auden: minus times minus equals plus, the reason for this we need not discuss", "url": "https://divisbyzero.com/2011/05/04/auden-minus-times-minus-equals-plus-the-reason-for-this-we-need-not-discuss/", "published_at": "2011-05-04T15:40:04+00:00" }, { "id": "01a0c55c-954d-723d-8d02-402a514abca6", "title": "A pyramidologist’s value for pi", "url": "https://divisbyzero.com/2011/04/27/a-pyramidologists-value-for-pi/", "published_at": "2011-04-27T20:41:34+00:00" }, { "id": "01a0c55c-954d-723d-8d02-402a51d5f06b", "title": "What do you want on your tombstone?", "url": "https://divisbyzero.com/2011/04/26/what-do-you-want-on-your-tombstone/", "published_at": "2011-04-26T04:07:27+00:00" }, { "id": "01a0c55c-954d-723d-8d02-402a5251341c", "title": "Happy birthday Uncle Leonhard, I hope you enjoy your new home", "url": "https://divisbyzero.com/2011/04/15/happy-birthday-uncle-leonhard-i-hope-you-enjoy-your-new-home/", "published_at": "2011-04-15T12:02:20+00:00" }, { "id": "01a0c55c-954d-723d-8d02-402a52d69130", "title": "Math books for young children", "url": "https://divisbyzero.com/2011/04/14/math-books-for-young-children/", "published_at": "2011-04-14T20:16:59+00:00" }, { "id": "01a0c55c-954d-723d-8d02-402a5369ce76", "title": "Albrecht Dürer’s ruler and compass constructions", "url": "https://divisbyzero.com/2011/03/22/albrecht-durers-ruler-and-compass-constructions/", "published_at": "2011-03-23T03:00:34+00:00" }, { "id": "01a0c55c-954d-723d-8d02-402a543c2ff7", "title": "A picture of frustration: Sam Loyd’s 15 puzzle", "url": "https://divisbyzero.com/2011/03/01/a-picture-of-frustration-sam-loyds-15-puzzle/", "published_at": "2011-03-01T19:26:13+00:00" }, { "id": "01a0c55c-954d-723d-8d02-402a54f221a4", "title": "Millay’s Euclid looks on Beauty bare", "url": "https://divisbyzero.com/2011/02/19/millays-euclid-looks-on-beauty-bare/", "published_at": "2011-02-19T22:07:04+00:00" } ] posts Claim your blog

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2026

3D-Printed Slices and Traces of Functions of Two Variables original ↗

1 Feb 2026

2025

Constructing a Large 251-Point String Art Cardioid original ↗

22 Nov 2025

A Laser-Cut Tromino Puzzle original ↗

1 Nov 2025

The Unknotting Number is Not Additive original ↗

9 Oct 2025

Mathematics Departments at Liberal Arts Colleges original ↗

12 Feb 2025

Magic Eye Image as an Animated GIF original ↗

31 Jan 2025

Type Math on a Mac—Remapping My Keyboard original ↗

18 Jan 2025

2024

Make a “Magic Eye” image using Excel original ↗

1 Dec 2024

Making the Mandelbrot Set with Excel original ↗

13 Nov 2024

Fold-and-Cut Turtle Tile original ↗

20 Aug 2024

Fold-and-Cut Hat and Spectre Tiles original ↗

14 Aug 2024

Cardioid Drawbridges original ↗

24 May 2024

Folding a Cardioid original ↗

14 Mar 2024

2023

Connections with mathematical terms original ↗

6 Nov 2023

Drawing a Celtic Knot original ↗

11 Oct 2023

Math class technology policy: Fall 2023 edition original ↗

23 Aug 2023

3D-Printable Aperiodic Monotiles and Aperiodic Monotile Coloring Book Pages original ↗

4 Jun 2023

2022

Halloween craft: FLEX-A-GHOUL original ↗

1 Nov 2022

Preorders and Finite Topological Spaces original ↗

28 Jan 2022

2021

My Two-Day Crash Course in PGFPlots and TikZ original ↗

28 May 2021

Essential Trigonometry for Calculus original ↗

10 Feb 2021

Puzzle: Let’s (Un)Do the Twist!original ↗

3 Feb 2021

Mathematicians’ Phone Passcodes original ↗

23 Jan 2021

2020

Make a Real Projective Plane (Boy’s Surface) out of Paper original ↗

8 Apr 2020

The Magnificent Möbius Band original ↗

29 Mar 2020

How to Present a Mathematical Proof or Problem original ↗

6 Jan 2020

2019

Homemade Klein Bottle original ↗

24 Dec 2019

Tales of Impossibility: Now Published!original ↗

13 Nov 2019

BraidTiles—A Mathematical Braid Puzzle original ↗

1 May 2019

A Numerical Crossword Puzzle original ↗

13 Mar 2019

The Most Imaginary Number… is Real!original ↗

13 Mar 2019

My First Crossword Puzzle original ↗

5 Jan 2019

2018

Make Your Own Pythagorean Cup original ↗

31 Dec 2018

A bad, but interesting, exam question original ↗

21 Dec 2018

Proof by Induction with a Difficult Base Case original ↗

7 Nov 2018

Proof Without Words: Gregory’s Theorem original ↗

29 Sept 2018

Möbius Band Ambigram original ↗

11 Sept 2018

Rubik’s Cube Tri-Hexaflexagon original ↗

22 Aug 2018

I Heart Cardioids original ↗

3 Apr 2018

Finite differences of polynomials original ↗

13 Feb 2018

Who was Pierre Wantzel? A translation crowdsourcing project original ↗

8 Feb 2018

2017

Math Crafts: Salt Designs, Newton Snowflakes, Fractal Christmas Trees, Paper Pentagons, and Flip Books original ↗

18 Dec 2017

The Division Symbol Goes Viral original ↗

15 Sept 2017

Advice for College Students original ↗

24 Aug 2017

The Math Behind a Reflected Double Rainbow original ↗

4 Jul 2017

Card Table Proof of the Pythagorean Theorem original ↗

30 May 2017

Seventeen Facts about 17 original ↗

14 Apr 2017

A Geometric Proof of Brooks’s Trisection?original ↗

30 Mar 2017

2016

Two More Impossible Cylinders original ↗

3 Oct 2016

Make a Sugihara Circle/Square Optical Illusion Out of Paper original ↗

6 Jul 2016

Sugihara’s Circle/Square Optical Illusion original ↗

5 Jul 2016

Measuring Tapes for Circles and Spheres original ↗

22 Apr 2016

Zip-Apart Möbius Bands original ↗

11 Apr 2016

A Trig-free Proof of Crockett Johnson’s Theorem original ↗

7 Apr 2016

A Geometry Theorem Looking for a Geometric Proof original ↗

23 Mar 2016

A Trisectrix from a Carpenter’s Square original ↗

11 Mar 2016

Good activity for an Introduction to Proofs class original ↗

25 Feb 2016

2015

Editing a Very Poorly Written Proof original ↗

10 Oct 2015

2014

Tangent lines to the sine function with rational slope original ↗

27 Aug 2014

Gabriel’s paper horn original ↗

26 Mar 2014

Undergraduate Math Bloggers original ↗

18 Feb 2014

2013

2013: the year of pi original ↗

9 Sept 2013

Using a kayak to measure the perimeter of a lake original ↗

4 Jul 2013

Countability of the rationals drawn using TikZ original ↗

17 Apr 2013

Greatest living mathematician and expositor?original ↗

12 Apr 2013

Bubble diagrams for functions in LaTeX using TikZ original ↗

9 Apr 2013

Circular reasoning: who first proved that C/d is a constant?original ↗

6 Mar 2013

Interview on Wild about Math!original ↗

27 Feb 2013

Editing mathematical writing original ↗

10 Feb 2013

2012

How I teach topology: an inquiry-based learning approach original ↗

16 Dec 2012

The Pigpen Cipher in Latex original ↗

9 Dec 2012

Online LaTeX editors original ↗

5 Dec 2012

How do you place incoming mathematics students?original ↗

18 Oct 2012

Ancient number systems in XeTeX original ↗

31 Aug 2012

Mathematics departments at liberal arts colleges original ↗

16 Aug 2012

Plato’s approximation of pi?original ↗

20 Jun 2012

Puzzler: a squarable region from Leonardo da Vinci original ↗

18 Jun 2012

Angle trisection using origami original ↗

1 Jun 2012

An interesting multivariable calculus example original ↗

19 Apr 2012

Parametric curve project for multivariable calculus original ↗

22 Feb 2012

2011

Cantor set applet original ↗

29 Oct 2011

Applet to illustrate the epsilon-delta definition of limit original ↗

29 Oct 2011

The danger of false positives original ↗

7 Oct 2011

A neat probability rule-of-thumb original ↗

15 Sept 2011

Advice for new college students original ↗

30 Aug 2011

A quick guide to LaTeX original ↗

17 Aug 2011

Highlights from MathFest 2011 original ↗

13 Aug 2011

The Japanese theorem for nonconvex polygons original ↗

22 Jun 2011

Some LaTeX odds and ends original ↗

9 Jun 2011

Extreme examples and counterexamples original ↗

6 Jun 2011

Hankel on Diophantus original ↗

31 May 2011

What shape are the golden arches?original ↗

11 May 2011

Auden: minus times minus equals plus, the reason for this we need not discuss original ↗

4 May 2011

A pyramidologist’s value for pi original ↗

27 Apr 2011

What do you want on your tombstone?original ↗

26 Apr 2011

Happy birthday Uncle Leonhard, I hope you enjoy your new home original ↗

15 Apr 2011

Math books for young children original ↗

14 Apr 2011

Albrecht Dürer’s ruler and compass constructions original ↗

23 Mar 2011

A picture of frustration: Sam Loyd’s 15 puzzle original ↗

1 Mar 2011

Millay’s Euclid looks on Beauty bare original ↗

19 Feb 2011