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February 1939 Popular Science
 [Table of Contents]
Wax nostalgic about and learn from the history of early
electronics. See articles from
Popular
Science, published 1872-2021. All copyrights hereby acknowledged.
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In the days before phone
apps could instantly calculate just about anything, many people relied on handy
cardboard calculators designed for specific tasks. One example is this two-sided
"20-in-1 Shop Guide," provided in 1966 by the Popular Science Book Club.
More elaborate cardboard calculators and cross-reference guides featured a
sliding element between the two outer pieces, similar to a slide rule. In many
ways, these devices are more convenient than phone apps because all the
information is visible at a glance, so you immediately know what they can
calculate. The images below can be printed and glued to cardboard, but be sure
to scale them correctly so the measurement marks remain accurate. I keep a few
of these taped to the undersides of my toolbox lids.
Popular Science Book Club 20-in-1 Shop Guide
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