During the period of national isolation, a mathematical tradition called wasan flourished in Japan. Though virtually unknown to Europeans before the Meiji Restoration, its practitioners, the wasanka, produced some results comparable to (and sometimes in advance of) those of mathematicians of the European Enlightment. This volume, a companion to Unger's earlier translation of solutions by Aida Yasuaki (1747–1817), focuses on problems that Aida most likely used as a teacher. Unger explains the reasons for believing this, and sheds further light on the intellectual milieu in which Aida worked by discussing other books by Aida, including one in which he describes Dutch techniques of navigation.