The Checkbook Balancer

Balancing credits and debits in a checkbook has long challenged many consumers. In 1972, late in the age of mechanical aids to computation, the Diamond Check Division of Diamond International Corporation introduced this small adding machine that fit in a checkbook.
The stylus-operated tan plastic non-printing adding machine has six orange plastic wheels and an orange plastic stylus. A long slot across the top of the instrument fits into a checkbook. Each wheel has ten indentations on each side. The frame has openings around each wheel on both sides. These are numbered from 0 to 9. Deposits are entered by rotating wheels on the front of the instrument, and debits are entered by rotating wheels on the back. A blue paper envelope gives instructions.
The machine is marked on the front: THE CHECKBOOK BALANCER (/) DEPOSIT TURN DIALS (/) CLOCKWISE. It is marked on the back: THE CHECKBOOK BALANCER (/) DEDUCT TURN DIALS (/) CLOCKWISE. It is also marked there: PAT. PEND. (/) DIAMOND INTERNATIONAL CORPORATION, and: U.S.A. It is marked on the paper case that holds the instrument: Diamond International Corporation, P.O. Bin 28, Arroyo Annex, Pasadena, California 91109.
Newspaper accounts indicate that this product was aimed particularly at women, as they were primarily responsible for balancing checkbooks. Devices were marketed to banks, who in turn sold them to customers for $3.00 or less. By April 1973 some 500,000 of the machines reportedly had sold. They would soon be replaced by inexpensive electronic calculators.
Alexander Auerbach, "Pocketbook Computer May Aid System of Checks and Balances," Los Angeles Times, February 11, 1972, p. F12.
Display Advertisement, The Washington Post, June 6, 1972, p. A4.
Display Advertisement, Los Angeles Times, April 24, 1973, p. G6.
Currently not on view
Object Name
adding machine
date made
ca 1972
Diamond International Corporation
Physical Description
plastic (overall material)
paper (overall material)
overall: 1 cm x 16.2 cm x 7.5 cm; 13/32 in x 6 3/8 in x 2 15/16 in
place distributed
United States: California, Pasadena
ID 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 Professor Shirley Surrette Duffy
Additional Media

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