Robert Talbert on The origin of the nabla symbol.
A cute number-theoretic puzzle from John D. Cook.
The shortest route from every Hubway station to every other. Hubway is a bike-sharing system and all its stations are within the city of Boston, but not surprisingly some routes go through Cambridge or Brookline, because Boston is not convex.
From math.stackexchange, examples of apparent patterns than eventually fail.
From Social Flow, Timing, Network and Topicality: A Revealing Look at How Whitney Houston Death News Spread on Twitter. (There was a 42-minute period where the news had been tweeted but almost nobody knew about it.)
Piotr Blaszczyk, Mikhail G. Katz, David Sherry, Ten Misconceptions from the History of Analysis and Their Debunking.
Over the last decade, baby teeth are a better investment than the stock market.
Math doesn’t suck, you do. Interesting, but crass and offensive. The way to convince people that math is awesome is not to insult them.
Most 3-pixel-by-3-pixel=squares in black and white photos lie near a Klein bottle in a nine-dimensional space.
Annie Keeghan, at Salon, writes Afraid of your child’s math textbook? You should be. Some interesting comments at Hacker News.