# Mental Calculation CV

Calculation CV A.W.A.P. Bouman

Birth date 19-09-1939. As a child of 2 years I knew the alphabet, being 3 years I could read the clock. At school 4 th class I knew all the 2×2 multiplications, they flew into my memory. At secondary school 1953 we learnt square roots. There the idea of sorting squares on same end figures: the squares of 7, 43, 57 and 93 all end on 49. Besides : 7+93=100, 43+57=100 43+50=93 and 7+70=57. After that the idea of sorting on 3 end figures struck me. 7,243,257, 493,507, 743,757 and 993, all their squares end on 049. After that all the squares till 1.000 were saved in my memory. This enabled me to do sqrts of numbers of 10 digits. About a year later I found a method for cubic roots, of numbers of 15 digits. In 1957 I got my school certificate, not on the mathematic department but on the commercial department. My mathematics are very weak. I am no mathematician, I am an arithmetician. It is a regrettable mistake that very good calculators automatically are very good mathematicians. Concerning me: even in the contrary.

During my working period calculation was a useful accessory, unfortunately I could not find other ones who did the same thing. One – very important – exception was my meeting with the famous Wim Klein in December 1959. There was something very amusing: in his opinion cubic roots by MC was impossible. After my demonstration and explanation he immediately understood my method.

I did nothing with my MC – why should I having no colleges and Klein lived in Switzerland. When I wanted to renew the contact in 1986 he was murdered shortly before.

The squares sport has never left me, so factorisation is my speciality. In Gießen at the MCWC in 2006 I was the only one with the full 100 points score on the prime numbers. In the MSO in England there are always ± 8 numbers of which to find the prime factors.

So for me in personal point of view factorisation is very interesting it gives me insight in the number world, I steadily train the squares.

During my professional life Mental Calculation was a useful accessory to me: for selling truck tyres one needs to know the axle load, the calculation of which was very simple to me. Thorough MC training did not happen.

In 1995 I retired.

In 2006 I met Gert Mittring, who advised me to go on with MC, “you have no idea how good you are”.

He stimulated me to participate in tournaments.

From that moment I started training intensively and made very good progress. MSO 2006, fully unprepaired a 7th ranking, 2007 5th ranking, 2008 4th ranking, 2009 3rd ranking.

My talent is especially creativeness, I have had many big compliments about the algorithms I found myself: to do cubic roots of 18 and 21 digits, “the cubic fives”, cubic roots of numbers ending on a five, structure in power calculation, my work with the Chinese remainder theorem, etc etc.

At regular times I organise a “mental calculation prodigee” weekend in my house. My guest are – of course – Gert Mittring, Jan van Koningsveld, Andy Robertshaw. Some others should like to come, the distance is the problem: Robert Fountain, George Lane.

After having obtained a third ranking in the World Championship MC 2009 – the toughest ever – in London Gert said “I am very proud of you”. This ranking was obtained after a year of intensive training.

© A.W.A.P. Bouman 2009