The Add-O-Matic adding machine (1947-1949) @jaapsch2

Uploaded July 2026 | Updated September 2026, 2 hours ago

This Add-O-Matic adding machine was made in Chicago from 1947 till 1949. It should not be confused with the earlier Add-O-Matic from 1937, which is a completely different machine, made by a different company, though also from Chicago.

For more information about this and other machines in my collection, please visit my website:
jaapsch.net/mechcalc

0:00 Introduction
0:23 Addition & Clearing
1:08 History
2:25 Mechanism
4:11 Outro

The Add-O-Matic adding machine (1947-1949)

The Pocket Counter, a small adding machine

$The Quixsum Fractional Adding Machine The Quixsum Fractional Adding Machine is an adding machine for lengths in feet, inches, and fractions of an inch. It was made in 1924. It is very rare as only about 600 were ever made. Stephen Freeborn has a nice video of it too: https://youtu.be/7f4Q-YwIhKw For more information about this and other machines in my collection, please visit my website: https://www.jaapsch.net/mechcalc/ 0:00 Introduction 0:12 History 1:19 Adding 4:04 Clearing 5:02 Opening case 5:02 Opening case 5:33 Mechanism 6:57 Rarity 7:57 Outro$

The mechanism of the Add-em toy adding machine