Olivetti Divisumma 24 Calculating Machine

Established as a typewriter manufacturer in 1908, the Italian firm founded by engineer Camillo Olivetti (1868–1943) began manufacturing a calculating machine in 1940. After World War II, it introduced a ten-key printing machine capable of division, the Divisumma 14. This is a later version of that machine, the Divisumma 24, which was introduced in 1956. Like many Olivetti products, these adding machines reflect the style of artist and industrial designer Marcello Nizzoli and have received attention for that reason. This example was manufactured after Olivetti acquired the Underwood Typewriter Company in 1959.
The machine has a gray metal case with a black lid. The yellow keyboard has a block of nine white number keys. Below these are three black keys with white dots for setting single, double, and triple zeros. To the right are two sets of four keys. Four of these are green, and relate to operations in the green register. The other four are black, and relate to operations in the black register (keys of one color are not grouped).
To the left of the numeral keys are the backspace key and the keyboard clearing key. Below them is the thumb add bar. Left of these are two levers with green knobs. One, marked A, predetermines automatic or non-automatic printing of the product. The other, marked R, is a repeat key. Further keys are to the left of these. The column indicator is above the keyboard.
The printing mechanism toward the back includes four digit wheels used to set dates, 13 digit wheels for numbers, and two type wheels right of the digit-wheels to print symbols. Totals are printed in red. The serrated plastic edge helps to tear the paper tape.
A mark on the top of the machine reads: underwood * olivetti. A mark on the back reads: Divisumma 24 Olivetti (/) MADE IN ITALY FABRIQUE EN ITALIE. A plate attached to the bottom has the serial number: 2D014738.
The machine also has a gray plastic cover, three paper tapes and two cords stored. The tapes are 8.8 cm. (3-1/2”) wide.
Compare 1979.0932.01.
The Kansas physician Richard L. Sutton Jr. reported when he donated the object to the Smithsonian Institution in 1979 that he found it “a meritorious machine, to which I have been strongly attached emotionally.”
S. Kicherer, Olivetti: A Study of the Corporate Management of Design, New York: Rizzoli Inc, 1990.
N. Shapira, Design Process Olivetti 1908–1978, [Ivrea, Italy]: Olivetti, 1979, pp. 56–57.
Olivetti, Instructions for the Operation of Tetractys Printing Calculator, 1958. (1979.0854.02).
Accession file.
Currently not on view
Object Name
calculating machine
date made
Physical Description
plastic (overall material)
paper (overall material)
rubber (overall material)
metal (overall material)
overall: 24.5 cm x 24.5 cm x 42 cm; 9 21/32 in x 9 21/32 in x 16 17/32 in
place made
ID Number
maker number
accession number
catalog number
Science & Mathematics
Calculating Machines
See more items in
Medicine and Science: Mathematics
Calculating Machines
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Richard L. Sutton, Jr.
Additional Media

Visitor Comments

4/1/2015 1:02:58 PM
Mark Glusker
This is actually an Olivetti Tetractys, not a Divisumma. The distinction is clear by the extra keys on the keyboard. The enclosure is exactly the same as the Divisumma, so it appears your machine has had the case swapped with a Divisumma (thus the "Divisumma 24" on the label at the rear of the case).
8/3/2015 4:54:50 PM
James McLeaster
I would just like to confirm Mark Gluskers' observation. It is a Tetractys 24. Not nearly as popular as the Divi 24 because of the duel adding machine feature that would let the operator do foot and crossfoot additions.
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