Uploaded September 2019 | Updated September 2026, 3 minutes ago

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The Lightning Adding Machine was made in Los Angeles from 1945 till about 1960. In 1950 the design changed, and here I compare the two versions.

My video demonstrating the Lightning Adding Machine:
youtube.com/watch?v=IeLaGvIyhv8

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

0:00 Introduction
0:22 Comparison
1:23 Subtraction
2:30 Clearing
3:09 Further differences
4:02 Instructions
4:22 Outro