Victor Model 780 Adding Machine

This ten-key printing manual adding machine has a black plastic top, green plastic keys, and a metal mechanism, handle, and base. The number keys are arranged in a block. To the left of these is a lever used to clear the place indicator. The place indicator is above the keyboard. Numbers with as many as eight digits may be entered. Back near the carriage are two levers. One, on the right, is marked “T” and set forward to obtain totals. The other, on the left, is adjusted for addition or subtraction. The printing mechanism is between these levers, with the paper tape to the back. Results up to nine digits long may be printed. The handle on the right side has a wooden knob painted black. The cover is of black cloth. The serial number, marked on the side of the base, is 531973.
According to Edwin Darby, this model was introduced in 1938. According to Office Machines Research, Inc., it was introduced in 1940. The serial number suggests that this example was made in 1947.
NOMDA’s Blue Book: Approximate January 1st Ages Adding Machines and Calculator Retail Prices, November, 1980, p. 57.
E. Darby, It All Adds Up: The Growth of Victor Comptometer Corporation, Victor Comptometer Corporation, 1968, pp. 77-90
Office Machines Research, Inc., section 3,21, February, 1940.
Currently not on view
Object Name
adding machine
date made
Victor Adding Machine Company
Physical Description
metal (overall material)
cloth (overall material)
paper (overall material)
plastic (overall material)
overall: 18.5 cm x 22.5 cm x 34 cm; 7 9/32 in x 8 27/32 in x 13 3/8 in
place made
United States: Illinois, Chicago
ID Number
maker number
accession number
catalog number
Science & Mathematics
Adding Machines
See more items in
Medicine and Science: Mathematics
Adding Machines
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Walton G. Banks, Inc.
Additional Media

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