@jcboy,
We're all decimel now, prior to that there was all sorts of weird amounts.
In Tudor England there was ahuge amount of different coins, pennies farthings, shillings florins, crowns, sovereigns, guineas.
All had their own exchange rate with each other, all designed to trick the innocent traveller. It was later simplified to pounds shillings and pence, but the coins kept the same names as before, so it wasn't simplified much.