Some time back, I reviewed a cool book about Fermi problems by Aaron Santos, then a post-doc at Michigan. In the interim, he’s taken a faculty job at Oberlin, written a second book on sports-related Fermi problems, and started a blog, none of which I had noticed until he emailed me. Shame on me.
Anyway, his new book is just out, and he’s running an estimation contest with a signed copy as the prize. So, if you’re the sort of person who enjoys Fermi problems, read his post then grab a convenient envelope and start estimating on the back. You have until June 1.