Have you heard of Arthur T. Benjamin? If not, you are in for a real treat. Arthur T. Benjamin is a mathemagician. He performs impossible feats of mental math. He has a Bachelor of Science with highest honors in Applied Mathematics from Carnegie Mellon University in 1983, a Master of Science in Engineering in Mathematical Sciences in 1985 and a Doctor of Philosophy from Johns Hopkins University in 1989; his PhD dissertation was titled "Turnpike Structures for Optimal Maneuvers". During his freshman year at CMU he wrote the lyrics and created the magic effects for the musical comedy, Kije!, in collaboration with author Scott McGregor and composer Arthur Darrell Turner. This musical was the winner of an annual competition and was first performed as the CMU's Spring Musical in 1980. (credit: Wikipedia)
Here is a video of him at TED talks doing incredible mental math!