This is the Summa de arithmetica, geometrica, proportioni et proportionalita, published by Luca Pacioli (1445-1509) in 1494. This was the most comprehensive mathematical text of the time and one of the earliest printed mathematical works. It contained not only practical arithmetic, but also algebra, practical geometry and the first published treatment of double-entry bookkeeping. On this page (f. 36v) Pacioli illustrates one of the methods of finger counting prevalent at his time in Italy.
Leonardo da Vinci drew the illustrations for Luca Pacioli's 1509 book De Divina Proportione (The Divine Proportion). Drawing of the Duodecedron Abscisus Elevatus Vacuus, consisting of 120 equilateral triangles, from the manuscript of the book.