Sfortunati, whose dates are not recorded, was a Siena-born teacher of arithmetic who worked through much of Italy and Sicily. His book, which went into at least six more editions by the year 1568, was influential, being one of the main sources for Tartaglia's General trattato de' numeri et misure, which has been called the best treatise on arithmetic to appear in the sixteenth century Sfortunati wrote his treatise along the lines followed by Borghi and Feliciano, and in his preface he acknowledges his indebtedness to them and to 'Maestro Luca dal Borgo dell' ordine di Santo Francesco' and to the operetta di Filippo Caladri Cittadino Fiorentino. Like these authors, he was a popular writer, as the seven editions of his book go to prove. His work is fairly complete as to the operations with integers and fractions, and is satisfactory as to the examples illustrating the Italian business life of the sixteenth century" (Smith, Rara Arithmetica, p. 174). Adams S1039. De Morgan, Arithmetical books, p. 16. Stillwell 234 Tomash S90. OCLC notes nine copies of this edition in North America.