Correction: I wrote << you can also use 163/9, 67/3, and (barely) 43/3. That is, 163/9, 67/9, and (barely) 43/9, i.e. the cube roots of exp(Pi*sqrt(d)) for d=163, 67, and 43 -- as you might have guessed from << [I've suggested that a CM mile should be exactly exp(Pi*sqrt(67)/3) feet long. :-)] NDE