This handheld electronic calculator has an array of ten digit keys and a decimal point key on the left with an array of function keys on the right. The main function keys are clear entry/clear, addition, subtraction, multiplication, division, percentage, and switching of the entered number and the result. Pressing a red F key changes these to memory keys, a square root key, an inverse key, and a squared key. The device has an eight-digit display and a compartment for a battery behind this.
A label stuck to the back of the calculator reads in part: aPF mark 30 (/) SLIDE RULE CALCULATOR. It also reads: MARK 30 (/) Model No. Further text reads: R-21114 (/) Serial No. At the bottom of this label are the words: APF ELECTRONICS INC. (/) NEW YORK, N.Y. 10022 (/) MADE IN U.S.A. A mark on the inside of the lid for the battery compartment reads: JAPAN (/) K-140032.
A June 11, 1975, advertisement in the New York TImes claims that the Mark 30 originally sold for $69.95 and was on sale at Macy's for $25.00. An October 1975 advertisement in the New York Times lists the APF Mark 30 as selling for $24.95, with an additional $3.95 for the adapter. An ad in the January 4, 1976, Chicago Tribune gives a price of $24.99. The price of the adapter is not listed. Advertisements for the calculator appeared in the Los Angeles Times in 1975 and 1976.
References:
Chicago Tribune January 4, 1976, p. 12.
New York Times, June 11, 1975, p. 6.
New York Times, October 23, 1975, p. 20.
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