Diversions Manifold

Mountain biking (an all to rare occurrence for me these days) is not a purely physical exercise; the brain is given a real workout, too. I'll concede straight away that it's by no means an intellectual exercise - I'm not necessarily thinking of anything at all (also a rare occurrence, one to be encouraged). But sometimes I become aware of the sheer mass of calculations that the brain is performing whilst I'm on the bike. It's thinking almost as hard as the legs are pumping. Of the many types of calculations buzzing around in my head, the most satisfying for me is the "hit or miss" question. I'm pedalling along a trail, at best upwards, and there's a rock in the way. Now, I can miss the rock with my wheels simply by steering away from it. But if things are tight and there isn't much room for manoeuvre, I start wondering if I'm going to bottom out with my pedals - which is usually a worse situation than hitting a rock with the wheel. Is t

Arithmetic, from University Department of Computer Science Years ago, Dad bought a lovely little book called Figuring, by the arithmetical genius Shakuntala Devi. It's a book on the joys of numbers. According to the rather short Wikipedia article on her: "On June 18, 1980 she demonstrated the multiplication of two 13-digit numbers 7,686,369,774,870 x 2,465,099,745,779 picked at random by the Computer Department of Imperial College, London. She answered the question in 28 seconds. However, this time is more likely the time for dictating the answer (a 26-digit number) than the time for the mental calculation (the time of 28 seconds was quoted on her own website). Her correct answer was 18,947,668,177,995,426,462,773,730. This event is mentioned on page 26 of the 1995 Guinness Book of Records" I am of course light years away from such talents, but I was never really terrible at it. However, I notice more and more that I have given up on trying to work out