We interrupt this revision to bring you the following complaint:
God, I hate working with non-decimal currency.
It took an irritating amount of math to figure out what £46 13s. 4d. works out to in Elizabethan marks. (Seventy, in case you were wondering.) Doing calculations where there are twelvepence (d) to the shilling (s) and twenty shillings to the pound, and a mark is worth 13s. 4d., is a good argument for modern currency systems.