Fair enough...
'Pooh', said the Wizard, 'is where we are now. The railway starts here and runs in a straight line via 39 intermediate and equally spaced stations to the terminus at Oz.
'Unfortunately, the railwaymen are on strike, so you'll have to go by bus. The bus goes along the Yellow Brick Road, which runs in a straight line from here to the outlying village of Bah, where it turns through a right-angle and goes in a straight line back to first railway station after Pooh. From there it goes in a straight line to the next outlying village, where it again turns through a right-angle and proceeds in a similar zig-zag fashion all the way to Oz, alternately calling at railway stations and outlying villages. Each of the 80 straight stretches of road is a different whole number of miles long. Rail distances are also whole numbers of miles.
'The fare is on ozzle per mile, but you needn't be alarmed, as all distances are as short as they can possibly be.'
I was alarmed, and it turned out I had good reason to be. My money was running short, for the Wizardry of Oz had been suffering from hyper-inflation recently.
Unfortunately the Wizard had vanished before I could ask him the vital question, HOW LONG IS THE Yellow Brick ROAD?
(Christmas problem from the 1976 Yorkshire Post, reprinted from one of my maths textbooks: extremely hard 10* difficulty, perhaps a bit easier with a computer program)