The contribution presents an opportunity for familiarisation with old monetary and measurement systems by means of past handbooks for merchants. It provides a detailed analysis of Christoff Rudolff’s handbook, dating back to the first half of the 16th century that instructs merchants in calculating and provides descriptions of operations: addition, subtraction, multiplication and division of fractions; nearly 300 practical exercises are included, in which he provides examples of calculations including actual monetary and measurement units for various European lands and cities. The examples date back to the period in which the handbook was written, thus providing data on money and units that were in use in Europe of the period. The contribution focuses on money in various environments. Rudolff’s data for the European area are compared to monetary units in the Slovene littoral and hinterland, as they were calculated by Sergij Vilfan in his studies nearly three decades ago.