The staplers and their customers in the low countries both accounted in terms of pounds, shillings and pence (librae, solidi and denarii), the centuries-old system accommodating two schemes, one based on the unit of a dozen (twelve pence in the shilling), and the other on the unit of twenty (shillings to the pound). The duodecimal unit fitted neatly into its own ‘hundred’ of six-score, used for certain commodities in Britain, but not into the ‘small tale’ hundred of five-score, by which other goods were commonly sold, for example fells at Calais or cloth when priced by the hundred ells. The great advantage of the duodecimal unit was that, unlike the score or the hundred of five-score, it was readily divisible by three. Some of this advantage of a duodecimal shilling was lost in England, because its constituent unit, the penny, was divisible in practice only into a half (the halfpenny, in Latin obolus, abbreviated ob.), and a quarter (the farthing, Latin quadrans). The difficulties caused by this were demonstrated in Chapter 6, when calculations of the custom and subsidy due on fells were examined. In the low countries, on the other hand, the penny was subdivided conveniently into 24 mites, or three units of account named in Flemish the engelsc or ingelsche and in French esterlin, ‘sterling’.

The awkwardness of the twenty-shilling pound was mitigated by the existence of another ancient unit, the mark, which expressed two-thirds of a pound, whether weight or money.