Knuth points out a very useful property of the Fibonacci number base: conversions between kilometers and miles.

*All you do is shift the digits!*

For example, say I want to convert 65

kmh to

mph. Well, 65

_{10} = 55 + 8 + 2 = 100010010

_{fib}, and shifting (

right) we have 10001001

_{fib}mph = (34 + 5 + 1)mph = 40

_{10}mph (it's actually closer to 41

_{10}mph).

Details of why this works are left as an exercise to the interested reader.