Mitlin, a 38-year-old computer expert, worked out the answer to the question faster than many computer users around him in the mental arithmetic competition held in this math museum. A spokesman for the museum pointed out that Mitlin broke the world mental arithmetic record set by Frenchman Le Muir in 1988. At that time, it took Lemaur 13.55 seconds, and I worked out something similar to umit Forest in my mind.