Category Archives: mathematics

Bertrand’s Box paradox: The answer is 2/3!!!

There are almost 200 comments now on my post about Bertrand’s Box Paradox yesterday. Let me reprise the problem and then give the solution the way I hit on it: There are three boxes: a box containing two gold coins, a box containing two silver coins, a box containing one gold coin and a silver […]

Bertrand’s paradox

Reader Peter sent me this paradox (it’s not really a “paradox” as I understand the meaning of that term, but a result that, like the Monty Hall problem, is deeply counterintuitive). It’s called Bertrand’s Box Paradox after French mathematician Joseph Bertrand, who raised it in an 1889 book on probabilities. The setup is simple: There […]

The other social media

by Grania While we are on the subject of social media, GooglePlus is one of the least popular. It’s never really been able to compete with Facebook; despite being moreorless the same, at least in its original intentions. One of the things I like about it is that as a result of its unpopularity there […]

Weird and slightly alarming – the chaos game

by Matthew Cobb This video from the excellent Numberphile YouTube channel shows a very simple game that has the most unexpected outcome. My only criticism of this video is that I’d like to be shown the explanation, even if it’s complicated! Maybe readers can help me.

More security lunacy: mathematician pulled from plane for . . . doing math

From Marginal Revolution, courtesy of reader Jósef, we have a bizarre tale of how our nation is being protected from terrorists. Here it is in its entirety (I’ve added the link to his university site): “Guido Menzio an economist at the University of Pennsylvania–author of Block Recursive Equilibria for Stochastic Models of Search on the Job among […]

Does the beauty and effectiveness of math in understanding the world prove anything?

One of the disadvantages of shopping for food early Sunday morning is that Krista Tippett’s “On Being” program is on National Public Radio at 7 a.m. And, of course, I have to listen, cursing to myself for an entire hour. Why do I do it, you ask? I could say that I need to keep […]


I win! And happy Pi Day!

An algebraic limerick

by Matthew Cobb Spotted on Tw*tter. I’ll give the source later, along with the explanation. Post your explanations below. If you know the answer already, please refrain from posting – if you work it out, go ahead! [EDIT: The correct answer appears in the first comment below! If you want to spend some time working […]

Some surprising sums—and a challenge

by Matthew Cobb This was tw**ted earlier today: 1+2+34–5+67–8+9 =100 12+3–4+5+67+8+9 =100 123–4–5–6–7+8–9 =100 123+4–5+67–89 =100 123+45–67+8–9 =100 123 –45 –67+89 =100 — Simon Pampena (@mathemaniac) December 9, 2015 There are five other sums (equations?) that give the same answer. Can you find them? Post your answers below.  

Two Google Doodles: one for a holiday, one for science

Today’s doodle in the U.S., and probably Mexico, features the Day of the Dead (click screenshot below), but I find the one in Ireland, sent by reader Grania, much more interesting, as it’s science-related. First, Dia de Muertos (yesterday and today), which I was lucky to see first-hand a few years ago in Mexico City: […]