The Math Less Traveled

Welcome to the 53rd Carnival of Mathematics! A somewhat shorter carnival this time, but I greatly enjoyed reading the submissions I did get, and I hope you do too.

• Meaghan Montrose at TutorFi presents ten tips for daily practicing your math skills.
• Erin at Note from the Teacher shares some tips on how to get tutoring, practice materials, and other math help for your child without coughing up a ton of money.
• Math Mama, aka Sue VanHattum, links to the Institute for Figuring, an amazing organization which is, to quote the “about” page,
  

  dedicated to enhancing the public understanding of figures and figuring techniques. From the physics of snowflakes and the hyperbolic geometry of sea slugs, to the mathematics of paper folding and graphical models of the human mind, the Institute takes as its purview a complex ecology of figuring.

  The site is well worth exploring! Math mama particularly likes their photo galleries, which show off crocheted explorations of hyperbolic geometry!

• Barry Leiba of Staring at Empty Pages explores the trigonometry of car doors. If you’re trying to get out of your car in a tight parking spot, which would you rather have, a wide door or a narrow one?
• Pat Ballew talks about the subfactorial operation !n, which counts the number of ways of reordering n things so that none of them is in its original position (known as derangements), and wonders where the notation came from.
• What could breastfeeding possibly have to do with the golden ratio? John Cook discusses rational approximations over at his blog, The Endeavour.
• Badal Joshi, a math grad student at Ohio State University, has a neat new blog, The Squared Circle. I especially like his recent series of posts on games and probability, but there’s lots of other great stuff as well.
• The Number Warrior, Jason Dyer, writes about an apparent bug in Wolfram Alpha. How can we trust Wolfram to get complex integrals right if they can’t even manage Babylonian number notation?
• Last but not least, Dave Richeson at Division by Zero has some beautiful GeoGebra applets for playing with the Japanese Theorem, which relates the radii of circles inscribed in triangulations of cyclic polygons.