When I think of the extremely complicated calculations we did in school involving farthings, ha'pennies, pennies, thrupenny bits, sixpences, shillings, florins, half-crowns to be multiplied, divided converted to highest denominator, added, subtracted, and all this at the age of ten or less, I can hardly believe we mastered it, (and calculators hadn't been invented then). But we jolly well did! And don't even think of ounces, pounds, stones, hundredweights, pecks, bushels, gills, pints, quarts, gallons, furlongs, rods, poles or perches!