My very first computer job required me to travel the length and breadth of the country to audit all of Railtrack's computers. Now, I took this job as a means to get out of driving fork lift trucks loading the british gypsum wagons (winter was approaching, and being one of these "namby pamby fair weather fork lift drivers"), and as such knew nothing.
I asked my boss how to get the capacity of the hard drive installed in these computers. He produced a 12" ruler, and proceeded to explain a complicated algebraic equation to discover the capacity based upon a hard drive's physical dimensions. I'd audited most of the east midlands before I figured out I'd been had