### If you have a question, someone else probably has it too…

I often tell my students, “When you have a question, ask, because you’re probably not the only one who’s wondering.” I heard the same thing when I was a student, but I still felt embarrassed to ask. What if I really was the only one? Wouldn’t I be slowing down class to ask? If no … More If you have a question, someone else probably has it too…

### Cantor’s Arch

Triumphal Arch: Arch of Titus, Rome Arc de Triomphe, Paris Washington Square Arch, New York Triple Arch: Arch of Constantine, Rome Arc du Carrousel, Paris Marble Arch, London Septuple Arch: ??? Cantor’s Arch: It seems to me that no arch is more triumphant than one that rests on a set of measure zero.

### Spontaneous Inequality

A fun problem making the mathematical rounds: if you give everybody some number of dollars (say you give 45 people \$45 each), and at every tick of the clock everyone with money chooses one random person \$1, how will the money eventually end up distributed? You might think it’ll stay approximately equal—”approximately” only because of … More Spontaneous Inequality

### Spice Blendoku

Since deciding to renew our lease for a second year, we’ve been trying to improve our apartment in several small ways: getting fabric for curtains, moving the recycling from a paper bag in the coat closet to a bin under the sink, re-gluing sections of doors that have warped apart, etc. One project we’ve had in mind … More Spice Blendoku

### How to draw an impossible triangle

If you’re like me, you like to doodle fun patterns. One of my favorite things to doodle is an “impossible triangle” that looks like three straight bars meeting in right angles, which can’t exist in real life: But I had trouble drawing an impossible triangle from memory, until through trial and error I came up with this … More How to draw an impossible triangle