Dutch genius Willem Bouman attempts new arithmetic record

Update Saturday, May 21: He did it again! Willem Bouman set his sixth world record mental arithmetic this afternoon by calculating the cube root from the number 7182 3714 0592 5428 0312 3253 9125 6146 6729. The answer he gave after 8 minutes and 46 seconds was 8955 4886 2009. And that was the right answer! Congratulations Willem! 

Bouman plans to set a sixth world record during TU/e's Open Day by becoming the first human being ever to draw the third-power root from a 36-digit number almost by heart. 

This means that he will try to decompose a 36-digit number (x) into three equal numbers (y) that, when multiplied, form the original number (y³ = x). A simple example is the number 27: the cube root of that number is 3, because 3 x 3 x 3 = 27. And the cube root of 64 is 4, because 4 x 4 x 4 = 64. Obviously, as the number gets bigger, pulling the cube root gets harder and harder, especially if you have to do most of the calculations by heart.

Earlier, in the 1970s and 1980s, another Dutch math genius, Willem Klein, set impressive records, such as the 73rd root of a 500-digit number. According to mathematicians, the special feature of Bouman's current attempt lies in the 12-digit answer - nobody has ever attempted this before. An interesting detail is that Klein learned part of his method from Bouman.

Having always had a great gift for mental arithmetic, Bouman developed this exceptional ability to great heights after retirement. He is the holder of no less than five world records, the last of which he set at TU/e in 2020.

He then succeeded in becoming the first person ever to write out at least ten five-digit numbers as the sum of four squares. The achievement received a lot of media attention at the time, including an appearance on Dutch television.

Stupid as a log

Bouman is a jack-of-all-trades when it comes to mental arithmetic. The retired tire salesman excels at, among other things, decomposing four-digit numbers into prime numbers, determining which day of the week is a particular date, pulling roots from 12-digit numbers, and pulling fifth-power roots from 25-digit numbers.

With his record attempts, Bouman wants to draw attention to the importance of mental arithmetic, especially among young people. His advice to students is: "Take your calculator and throw it in the garbage. Otherwise you'll become as lazy as a sloth and as stupid as a log."

A special jury has been assembled for the record attempt, consisting of mathematicians Benne de Weger and Tom Verhoeff. If the record is approved, it will be credited to the recordholders.org site, just like Bouman’s previous records.

Absolute silence

The record attempt will take place on Saturday, May 21 from 1:30 p.m. in the Blauwe Zaal in the Auditorium (map). The event is open to everyone, as long as there is room. Please note that absolute silence is desired during the record attempt. So please turn off your cell phone. After the record attempt, Willem Bouman will explain his technique, and he is available to answer questions and for a meet & greet.

Would you like to learn (better) mental arithmetic yourself? Willem Bouman has written a book (in Dutch) about his gift, in which he explains how he works. The most important advice: learn a number of tables by heart and practice a lot!