Gas stations with old fuel pumps with mechanical meters are worried because they don't go above $3.999/gal without an expensive retrofit. http://www.usatoday.com/money/industries/energy/2008-05-17-old-gas-pumps_N.h... It occurred to me that those things are mechanical multipliers with four-digit accuracy. How do they work? In the trade the part that does that is called the "computer" or "mechanical computer". At the page above you see a glimpse of one. PMP Corp., mentioned in the article, sells Veeder-Root meters. VR's pages about them have interesting jargon: http://www.veeder.com/page/VR104Pump http://www.veeder.com/page/VR10Pump This FAQ page has links to various PDFs with photos and diaagrams: http://www.pmp-corp.com/FAQs.asp?FAQMID=3&NumFaq=10&bmode=Main They also have things called "non-computers"! I think they just measure volume & don't multiply out the price. Funny that these and the Babbage machine have been in the news so close together. --Steve