The Fold-and-Cut Theorem

Courtesy Mental Floss:

The fold-and-cut theorem, which first appeared in 1721—and was later proved by MIT computer scientist/computational origami wizard/former child prodigy Erik Demaine—asserts that any shape comprised of straight lines can be made from a single cut if you can just figure out the right way to fold the paper.

Fidget Spinners

The Happy Ending Problem

Quanta Magazine recently published a nice description of the decades-old “happy ending” problem: https://www.quantamagazine.org/a-puzzle-of-clever-connections-nears-a-happy-end-20170530/

World’s Largest Musical Instrument

Watch a musician play the world’s largest instrument, an organ built by a Pentagon mathematician in Luray Caverns, Virginia. (This was a favorite destination of mine when I was a boy.)

Source: http://www.pbs.org/newshour/updates/mother-nature-pentagon-mathematician-created-worlds-largest-instrument/

Heat Index

Source: https://www.facebook.com/petedelkus/photos/a.127955303946093.30575.121420087932948/1521856847889258/?type=3&theater

Monotonic Monotony

Source: https://www.facebook.com/MathWithBadDrawings/photos/a.822582787758549.1073741828.663847933632036/1767946159888869/?type=3&theater

Hilbert’s Infinite Hotel Paradox

TED-Ed made a very good video describing the Infinite Hotel Paradox, a thought experiment to describe how injective (one-to-one) functions can be used to examine countably infinite sets.

Single-Digit NFL scores

Source: https://www.facebook.com/maanews/photos/a.170415820418.120984.153302905418/10154903882580419/?type=3&theater

Stay Focused

From Kirk Cousins, quarterback of the Washington Redskins:

Sometimes our guests ask why I have this hanging above my desk. It’s an old high school math quiz when I didn’t study at all and got a C+… just a subtle reminder to me of the importance of preparation. If I don’t prepare I get C’s!

Source: https://www.facebook.com/redskins/photos/a.118304319573.96677.102381354573/10155470824244574/?type=3&theater

Pizza Hut Pi Day Challenge: Index

I’m doing something that I should have done a long time ago: collecting a series of posts into one single post. The following links comprised my series on the 2016 Pizza Hut Pi Day Challenge.

Part 1: Statement of the problem.

Part 2: Using the divisibility rules for 1, 5, 9, 10 to reduce the number of possibilities from 3,628,800 to 40,320.

Part 3: Using the divisibility rule for 2 to reduce the number of possibilities to 576.

Part 4: Using the divisibility rule for 3 to reduce the number of possibilities to 192.

Part 5: Using the divisibility rule for 4 to reduce the number of possibilities to 96.

Part 6: Using the divisibility rule for 8 to reduce the number of possibilities to 24.

Part 7: Reusing the divisibility rule for 3 to reduce the number of possibilities to 10.

Part 8: Dividing by 7 to find the answer.