This book deals with one of the earliest surviving "abbacus" treatises, one that is by far more orderly than any of the extant predecessors and is also the first to contain a presentation of algebra. The book contains an edition and an English translation of a manuscript from c. 1450. In addition, it features an extensive discussion of the contents of the treatise and its location within early abbacus culture.

Jacopo, His Treatise, and Abbacus Culture.- Three Manuscripts.- The Abbacus Tradition.- The Contents of Jacopo's Tractatus.- Algebra.- Jacopo's Material and Influence.- The Vatican Manuscript Edition and Translation.- Edition and Translation Principles.- The Text.