What's the point of working through these diabolical questions? What's the point of making up these questions? Are they just ‘a madman's fly trap’, as the plots of a mystery writer (John Dickson Carr) that I much enjoy have been described? Obviously, I think there are good points, otherwise I wouldn't be writing this book, and would not be keeping myself sequestered nor neglecting important household tasks.

The first point is that to become a scientist one does need to develop awareness of the ways in which experimental data are turned into conclusions. How was Avogadro's number evaluated? How did Millikan (of the oil-drop experiment) determine the size of the charge on an electron? These were things I had to write about as an undergraduate, and I had to do the calculations too. Neither then nor now did I see the great relevance of this to biochemistry, but I did begin to see how hard-won are scientific ‘facts’, and I certainly realised then that I could manage handling the numbers, and using such horrors as five-figure logarithmic tables, long before the arrival of calculators.

This leads to the next point – doing problems helps to improve one's mathematical skill, and gives the confidence to believe that one has such skill.