Armed with only pen, paper and his own brain, the 82-year-old Dutchman Willem Bouman from Alphen aan den Rijn has managed to solve a particularly difficult calculation. He calculated the cube root of a number of 36 digits. It took him 8 minutes and 46 seconds to do that. Bouman did this on Saturday at the open day of Eindhoven University of Technology (TU/e), and according to the university Bouman is the first to have ever achieved this.
The number he had to calculate the cube root of was 718,237,140,592,542,803,123,253,912,561,466,729.
“The first thing I looked at was the last four numbers. Then I can immediately tell what the last three digits of the answer are. There is a very clear structure in the numbers, I’ve been working on that for 70 years, I can just see that,” Bouman explains afterwards.
He is calculating every day. “There’s something compulsive about it. When I cycle and I see a telephone number on a truck, I start calculating. When I see a ship with a registration number, I see if I can factor that number, I can’t stop it. It’s on my hard drive. If you want me to stop, you must separate my head from my torso.” Bouman already had several world records to his name. This successful attempt earns him a seventh.
The first assignment Bouman had been given on Saturday went wrong, he gave the wrong answer. Then he got the new number. “You are automatically a bit stressed, people have expectations of you. I realized fairly quickly that the first attempt went wrong. I’ll take a look later to see if I can find the nature of the short circuit. For a problem you have to make a generous number of different calculations, so the possibilities for errors are plentiful. I have trained for months, in almost all cases this goes well.”
Because the first attempt was unsuccessful, Bouman took a little more time on his second attempt. “That assignment went just a little bit better, I had the momentum. At the end I slowed down a bit, because I didn’t want to make a second mistake. I constantly check the calculations. I don’t care about time, I just think about the right answer.”
That correct answer was 895,548,862,009. Bouman looks back with satisfaction on his performance. “Mental arithmetic is without a doubt top sport. Now I’m going to rest first. The moment something special comes again, I will think about whether I will make an effort or whether I will spare myself.”
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