Magical Numbers

Daniel Gilbert wrote an excellent column for the Grey Lady today outlining the issue of irrationally favored numbers. Coincidentally, I taught classes today focusing on numbers and measuring units, sort of a pet interest of mine. Though I didn't bring up my dozenal society fantasies, or Swedenborg's octal counting system, I did mention the lesson of ring sizes in Sweden, which frequently utilize fractions of millimeters rather than the decimal counterparts to more easily help customers find appropriate their appropriate ring size and limit the range of sizes a jeweler must stock.