Monthly Archives: November 2009

Who Am I?

An excellent puzzle from JD2718: There are five true and five false statements about the secret number. Each pair of statements contains one true and one false statement. Find the trues, find the falses, and find the number. 1a. I … Continue reading

Posted in challenges, logic, number theory, puzzles, teaching | Tagged , , | 13 Comments

m-bracelets code

[15 January 2013: updated code to work with the latest versions of fgl and graphviz. Thanks to Conal Elliott for the updates!] By popular demand, here is the Haskell code I used to generate the images in my previous post. … Continue reading

Posted in arithmetic, computation, links, pictures, programming | Tagged , , , , | 3 Comments


It is easy to generalize number bracelets to moduli other than 10—at each step, add the two previous numbers and take the remainder of the result when divided by m. Here are some pretty pictures I made of the resulting … Continue reading

Posted in arithmetic, fibonacci, iteration, pattern, pictures, sequences | 6 Comments

One of these things is not like the others…

Hat tip to Tanya Khovanova.

Posted in pattern | Tagged , | 9 Comments

Number bracelets

Recently I’ve been volunteering with the middle school math club at Penn Alexander, a PreK-8 school in my neighborhood. Today we did (among other things) a fun activity I’d never seen before, called “number bracelets”. The students seemed to enjoy … Continue reading

Posted in arithmetic, iteration, pattern, sequences, teaching | Tagged , , , | 12 Comments


A fun game I discovered recently, minim. In each level you start out with a network of numbered nodes, and the object is to successively combine the nodes according to certain mathematical rules in order to end up with only … Continue reading

Posted in games, links | Tagged , | 1 Comment

Logicomix: An Epic Search for Truth

I recently acquired a copy of Logicomix: An Epic Search for Truth, by Apostolos Doxiadis and Christos Papadimitriou, with art by Alecos Papadatos and Annie Di Donna. It defies categorization: is it a comic book? A biography? A book of … Continue reading

Posted in books, logic, review | Tagged , , , , , , | 2 Comments