Adam Ries wrote the most popular German textbook on arithmetics in Early Modern History, Rechenung auf der linihen vnd federn. This contribution takes a systematic look at the didactic benefits of Ries' book by comparing it with the contemporary textbook by Johannes Widmann. The analysis covers three levels: the mathematical content of both textbooks, the design of their main text units—explanations and exercises—as well as the specific utilization of grammar, vocabulary, and notational schemes by Ries and Widmann. In contrast to (...) Widmann, Ries tailored his book to the needs of his audience. He selected and structured the mathematical content according to the practical needs of merchants and craftsmen without denying traditions like the abacus-style calculating. His explanations and exercises followed the usual rules of arithmetic textbooks but showed great flexibility in adapting to the learning process of the reader. This was supported by a stereotypical linguistic style that helped the reader to get through the text quickly. (shrink)