Ah, yes, the heady days in junior school (UK) adding up columns of pounds shillings and pence, Yards, feet and inches, Tons, hundredweights, stones, pounds and ounces, all with a vulgar fraction column if appropriate. Get beyond school and your employer would have one or more of these
http://www.vintagecalculators.com/html/comptometer.htmlsomewhere working out your wages (or you may be the operator of it, as my first wife was)
Even copying down your homework question from the blackboard was a herculean task and prone to error.
Marv rightly refers to this as the inferial system. Quite why the US grimly hangs on to it for linear measurement is a mystery. But then, we thought it was normal in those days.
Anyway, enough of my rambling, I must continue my search for that old school wooden rule marked in 11ths.
Ray