the word calculus itself has stories to tell. It comes from the Latin root calx, meaning a small stone, a reminder of a time long ago when people used pebbles for counting and thus for calculations. The same root gives us words like calcium, chalk, and caulk. Your dentist might use the word calculus to refer to that gunk on your teeth, the tiny pebbles of solidified plaque the hygienist scrapes off when you go for a cleaning. Doctors use the same word for gallstones, kidney stones, and bladder stones.
