by Guy Spriggs
In organizing its spring 2016 information meeting for majors, the UK Department of Mathematics solicited faculty to give the closing address. Professor Richard Ehrenborg volunteered, but suggested a less traditional approach.
“I said I wasn’t going to give a talk,” he recalled. “I was going to do a show.”
Instead of giving a lecture on new developments in the field or solving complex equations on the chalkboard, Ehrenborg led volunteers and spectators through tricks involving playing cards and simple geometric shapes. In short order, he was able to predict a single card’s location in a shuffled deck and prove that 168 and 169 are actually equal to each other.
But these were no mere sleight of hand illusions – as Ehrenborg points out, these intriguingly simple tricks all demonstrate valuable mathematical principles. These efforts are also