This unpretentious little book could almost be taken as a symbol of the third component in the collection of George A. Plimpton: "reading, writing and ‘rithmetic." It intends to teach commercial arithmetic, starting from the most elementary level to explain numbers and their positions as designators of units, tens, hundreds, and so forth. On the opening displayed a reader has noted the method for calculating differences in income for those who invest varying amounts of money at different times. Graphically clear are the various earnings of Piero, Polo and Zuanne. Their names, and indeed the entire text, are in the local vernacular: Venetian dialect, not Italian. Abbacus, or commercial arithmetic, was solidly vernacular, Latin being reserved for the abstract studies of the universities.