Jaap Scherphuis | The Business and Master adding machines @jaapsch2 | Uploaded January 2021 | Updated October 2024, 2 hours ago.
The Business adding machine was a simple troncet-type adder that was made in Belgium in the late 1920s. The Master adding machine was a later development with some rather ludicrous features.

For more information on these and other calculators in my collection, please visit my website:
jaapsch.net/mechcalc

0:00 Introduction
0:14 Business
0:28 Addition
1:27 Clearing
1:37 History
3:10 Master
5:25 Other versions
6:28 Cyrille Alphonse Hankard
7:13 Outro