Named for the famous German arithmetician Adam Ries (1492–1559), author of the first German arithmetic books, which were used over more than two hundred years and which explain the procedure of calculations in a clear manner. Ries made an effort to help the man in the street to appreciate arithmetic, which was considered at that time to be difficult. In 1539, Ries was appointed to the Churfürstlich Sächsischen Hofarithmeticus. (M 30478) _ _.