Die leichtverständliche Schule für den Umgang und das Rechnen mit der BRUNSVIGA 13 R
Brunsviga Maschinenwerke AG., Braunschweig
211mm × 146mm × 3mm
This is the basic manual for the Brunsviga 13 R mechanical calculator in German. It explains the four arithmetic operations of course, but also covers various applications and methods including percentage calculations and interest. There is even a section on taking square roots. There are various tables for interest calculations and for imperial weights. At the back an extra page has been pasted in which explains that the Brunsviga 13 RK has an extra switch with which you can select which registers to clear. The booklet has a copyright date of 1950.