(You must register with the MAA to attend this lecture; you can register at https://www.surveymonkey.com/s/2013CoMBenjamin .)
From the MAA's description: "Art Benjamin is a mathematician and a magician. In this performance, he will demonstrate and explain how to mentally multiply numbers faster than a calculator, how to memorize pi to 100 places, how to calculate the day of the week of any date in history, and other amazing feats of mind. He has presented his mixture of math and magic to audiences all over the world."
The exact time and location of the lecture haven't been announced yet. MAA lectures usually require pre-registering; we'll link to the registration form when it goes live.
More details are http://www.maa.org/meetings/calendar-events/the-magic-and-math-of-mental-calculation