Hewlett-Packard HP-35 Handheld Electronic Calculator

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The HP-35 was the first handheld electronic calculator to display all the functions represented on a slide rule. It has a black plastic case. It has a total of thirty-five square or rectangular plastic keys. These include ten digit keys, a decimal point key, and a pi key, all colored tan. In addition there are four arithmetic function left of the digit keys, a relatively long enter key, a change sign key, an enter exponent key, a clear x key, and a clear key, all in blue. Additional black keys are for powers, logs to base ten, natural logs, exponents, square roots, trigonometric functions (sine, cosine, tangent and the inverses of these), simple inverses, exchange, roll down, store, and recall. Above the keys is an on/off switch. There is no hole next to the switch to indicate that the display is on, as there was in the very first HP-35 calculators. Behind the switch is a red LED display which shows results. Numbers with absolute value between one hundredth and 10 billion are given in decimal form. Smaller or larger ones appear in scientific notation, with the appropriate power of ten occupying the three rightmost digit places (two for digits, one for a sign). The negative sign for the result, if needed, is at the far left. A mark on the front edge of the calculator reads: hp HEWLETT•PACKARD.
The back of the calculator has a plug for a three-prong power adapter, a compartment for a battery pack, four rubber feet, and a sticker entitled: HP-35 INSTRUCTIONS. Text below the sticker reads: HEWLETT-PACKARD (/) 3.75V 500MW (/) MADE IN USA PATENT PENDING. A sticker inside the battery pack reads: PROPERTY OF (/) WILLIAM SOMMERWERCK. Another sticker there reads: HEWLETT-PACKARD (/) SER.NO. 1143A 37972. A red sticker on the lid of the battery pack reads: CAUTION (/) USE ONLY H. P. BATTERY PACK (/) MODEL NO 03501A (/) OTHER BATTERIES MAY DAMAGE CIRCUITS.
In addition to the calculator, the gray plastic case contains a power adapter labeled in part HEWLETT - PACKARD (/) MODEL 03502A. It also includes a battery pack, a carrying pouch, and an HP-35 Operating Manual. The owner’s portion of the warranty is stored in the back of the manual and gives a date received of 8/4/72.
The donor, William Sommerwerck, gave the calculator in memory of his aunt, Miss Jeanette Fox, who gave him the money to buy the calculator.
W.A.C. Mier-Jedrzejowicz, A Guide to HP Handheld Calculators and Computers , Tustin, California: Wilson/Burnett Publishing, 1997, pp. 36-39, 132.
David G. Hicks, The Museum of HP Calculators, http://www.hpmuseum.org/, accessed July, 2014.
Thomas M. Whitney, France Rodé, and Chung C. Tung, “The ‘Powerful Pocketful’: an Electronic Calculator Challenges the Slide Rule,” Hewlett-Packard Journal, June 1972, pp. 2–9.
Currently not on view
date made
Hewlett-Packard Company
place made
United States
Physical Description
plastic (case; keys; display cover; presentation case material)
metal (circuitry material)
paper (manual material)
overall: 1 1/4 in x 3 1/4 in x 6 in; 3.175 cm x 8.255 cm x 15.24 cm
ID Number
accession number
catalog number
Credit Line
Gift of William Sommerwerk in memory of Miss Jeanette Fox
See more items in
Medicine and Science: Computers
Handheld Electronic Calculators
Computers & Business Machines
Data Source
National Museum of American History


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