Harrelson News–2000
Mathematical Magic Show
by Richard Chandler
For several years I have been performing a mathematical magic show which I originally inherited from Bob Silber. Most of the tricks are the "self-working" type (this means that they do not require sleight of hand or elaborate paraphernalia). Instead, they depend on a little bit of hidden mathematics or logic to work their effect. Usually, I request the services of a volunteer to share a piece of information (a card, number, etc.) to which I am not privy with the rest of the audience. The object of the trick is for me to then discover through "magic" the hidden piece of information. One of the most effective of these tricks has the volunteer place a balled-up napkin under one of three apparently identical plastic cups (my back is turned), take a practice swap of the two empty cups, and then swap cups two at a time, telling me the positions as they are exchanged. After the volunteer does this several times, I turn around and pick up the cup having the napkin under it.
After demonstrating each trick I explain why it works. These explanations usually require a little mathematics, normally at the level of high school algebra. The ultimate purpose behind my doing this is recruitment: to show that the mathematics faculty at N. C. State are not the stodgy, absent-minded professor types that media typically portray; that it might be a good college to consider when the time comes to decide where to spend the next four years.
In the last several years I have visited seemingly innumerable high schools (including a trip to Hendersonville and a trip to Manteo during the same week). Some of the more unusual venues include the Governor's School at St. Andrew's Presbyterian College in Laurinburg, the Eastern North Carolina School for the Deaf in Wilson, several high school and college clubs, and Beaufort County Community College. Last spring I visited the school on Ocracoke Island. I performed the show there twice: once for the entire high school (24 students) and once for the entire middle school (33 students)!