I have researched and written about methods of mental calculation over the years, and I’m often surprised at the ingenuity evident in the mathematical methods developed specifically for it. Based on my Lightning Calculator series of essays here, I’ve created a new 2011 calendar titled Lightning Calculation. It’s a unique, interactive calendar for developing abilities in mental calculation. You can download a free PDF file for printing on your computer, or if you prefer, order it for delivery through Lulu.com. I also think it might be a nice thing to make as a Christmas gift for someone interested in this sort of thing, or for displaying in a math classroom.
NOTE: If you choose to have the calendar professionally printed by Lulu.com rather than on your own printer, through December 31 you can enter the code REMARKABLEYEAR305 at checkout for 20% off the price of $17.60. The Lulu site is also posting daily coupon codes in December here.