This handheld electronic calculator has an array of ten white digit keys and five black keys for the four arithmetic operations and percentage. Red keys are for a decimal point, EX, clear entry/clear, equals, four memory functions, and D (display). A vacuum fluorescent display for eight digits and a decimal point is behind the keys. A battery compartment is at the top.
A mark above the keyboard reads: aPF MARK 25/MEMORY. A silver-colored paper tag on the back gives operating instructions. Toward the bottom of this tag it reads: APF ELECTRONICS INC (/) MODEL MARK 25 (/) SERIAL # K55342 (/) THIS CALCULATOR TO BE USED ONLY WITH APF LISTED A.C. ADAPTER MODEL 710 OR MODEL 716 (/) MADE IN U.S.A. A mark inside the lid of the battery case reads: JAPAN (/) K-140032.
A February 1975 advertisement in the Los Angeles Times indicates that the APF Mark 25 sold for $24.95 with an additional $4.95 for the power adapter. A November 1975 advertisement in the New York Times indicates that the APF Mark 25 pocket calculator (with eight-digit display) regularly sold for $19.95 and could be purchased for $17.95, with a few dollars more for the power adapter. A February 1976 advertisement in the Los Angeles Times indicates that the APF Mark 25 sold on clearance for $19.99.
Los Angeles Times, February 28, 1975, P. A26.
New York Times, November 2, 1975, p. 46.
Los Angeles Times, February 27, 1976, p. B9.
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