I love mathematics. And I love magic too. What about combining both of them and present as the genius mathemagician, like Arthur Benjamin did in this presentation. It reminds me of India's own Sakuntala Devi, one of the best known wizards of Mathematics and lightning calculations.
For those who know little or nothing about Sakuntala Devi, here is a brief introduction from wiki:
Shakuntala Devi is a calculating prodigy who was born on November 4, 1939 in Bangalore, India. Her father worked in a circus as a trapeze and tightrope performer, and later as a human cannonball. Her calculating gifts first demonstrated themselves while she was doing card tricks with her father when she was three. They report she "beat" them by memorization of cards rather than by sleight of hand. By age six she demonstrated her calculation and memorization abilities at the University of Mysore. At the age of eight she had success at Annamalai University by doing the same.
Unlike many other calculating prodigies, for example Truman Henry Safford, her abilities did not wane in adulthood. In 1977 she extracted the 23rd root of a 201-digit number mentally. On June 18, 1980 she demonstrated the multiplication of two 13-digit numbers 7,686,369,774,870 x 2,465,099,745,779 picked at random by the Computer Department of Imperial College, London. She answered the question in 28 seconds. However, this time is more likely the time for dictating the answer (a 26-digit number) than the time for the mental calculation (the time of 28 seconds was quoted on her own website). Her correct answer was 18,947,668,177,995,426,462,773,730. This event is mentioned on page 26 of the 1995 Guinness Book of Records ISBN 0-553-56942-2.