May be of interest to you:<div><br></div><div>Possibly the oldest mathematical instrument<br><p></p><style type="text/css" style="display: none;">P {
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</style><div><br></div><div><a href="https://cacm.acm.org/blogcacm/technical-marvels-part-2-lebombo-and-ishango-bones/" style="font-family: &quot;Trebuchet MS&quot;, Arial, serif; font-size: 14px;"><span lang="EN-US" style="color: blue;">Technical Marvels, Part 2: Lebombo and Ishango Bones – Communications of the ACM</span></a></div></div><div><br></div><div>Best wishes,</div><div>Herbert Bruderer</div>