Uploaded July 2017 | Updated September 2026, 1 hour ago

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The Walther RMKZ is a mechanical calculator of a standard Odhner pinwheel type.

It would have been black originally. The hammer grey enamel was probably added in the 1950s or 60s when that was fashionable.

For more information, visit my website:
jaapsch.net/mechcalc

0:00 Introduction, history
1:31 Addition
2:25 Subtraction
3:12 Clearing
3:39 Overflow bell
4:38 Multiplication
6:12 Shortcut multiplication
7:09 Division
9:58 Outro