Monroe Model IQ-213 Calculating Machine

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Authors in the 19th century marveled that machines could carry out arithmetic operations, which had often been associated purely with human intelligence. In the mid-20th century the Monroe Calculating Machine Company, a division of Litton Industries, introduced an electrically operated calculating machine that could store numbers entered to be used in several mathematical operations. They hailed this memory feature of calculating machines as an extension of artificial intelligence, naming the machine the “IQ-213.”
The full-keyboard, non-printing and electrically operated modified stepped drum calculating machine has a dark gray metal frame with a light gray metal carriage and keyboard. The keys are plastic. The ten columns of color-coded digit keys have nine keys in each column. Ten numeral dials on the keyboard display the amount entered in the memory. The machine has some 18 function keys.
The movable metal carriage has a row of nine plastic tab stops above three rows of dials. The top row of dials is divided into two sections, with ten dials on the left and 11 to the right. The left dials are revolution register dials that show multipliers in black or quotients in red. These do not have a carry. The right dials also register the multiplier in multiplication and the quotient in division and have a carry.
Above the black right dials is a row of eight red and one yellow plastic buttons. The red buttons are tab stops for the carriage, the yellow button releases the red ones. The second row contains 21 dials (for the results of addition, subtraction, and multiplication), and the third row has ten dials (for the multiplier). A cord that plugs into the back and a light tan plastic cover are present.
The machine is marked in raised letters on the front and back: MONROE; IQ-213 (/) THE CALCULATOR WITH A MEMORY. It is marked on both sides: MONROmatic. A tag attached to the bottom of the case reads: MODEL IQ - 213 (/) SERIAL B852353. The cord and plastic cover are marked: MONROE li.
For related documentation, see pamphlet 1988.0663.02, which is copyrighted 1963. Monroe filed for a trademark for the phrase “IQ-213” in 1962, and obtained the registration in 1963.
This machine was purchased by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, from Litton Business Systems for $1,085.
Accession file.
U.S. Patent and Trademark Office, Trademark Registration Number 754123, August 6, 1963.
Currently not on view
date made
Litton Industries
Physical Description
plastic (overall material)
metal (overall material)
overall: 22.5 cm x 45.8 cm x 41 cm; 8 27/32 in x 18 1/32 in x 16 5/32 in
ID Number
catalog number
maker number
accession number
Credit Line
Transfer from National Aeronautics and Space Administration
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Calculating Machines
Data Source
National Museum of American History


This looks like the machine on Katherine Johnson's desk

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