This is the small abacus of <a href="//commons.wikimedia.org/w/index.php?title=Muhammad_ibn_M%C5%ABs%C4%81_al-Khw%C4%81rizm%C4%AB&amp;action=edit&amp;redlink=1" class="new" title="Muhammad ibn Mūsā al-Khwārizmī (page does not exist)">Al-Khwārizmī</a> abacus with base-five/ten. All upper beans have the five values, and all down beans has the ten values. Hypothetically, this kind of abacus was used on the paleography of modern numerals. It is assumed to have originated because <a href="//commons.wikimedia.org/wiki/Human" class="mw-redirect" title="Human">humans</a> have ten <a href="//commons.wikimedia.org/wiki/Finger" class="mw-redirect" title="Finger">fingers</a>.
<a href="//commons.wikimedia.org/w/index.php?title=Muhammad_ibn_M%C5%ABs%C4%81_al-Khw%C4%81rizm%C4%AB&amp;action=edit&amp;redlink=1" class="new" title="Muhammad ibn Mūsā al-Khwārizmī (page does not exist)">Al-Khwārizmī</a>
born around 780 and died around 850
<a class="external free" href="https://en.wikipedia.org/wiki/Muhammad_ibn_Musa_al-Khwarizmi">http://en.wikipedia.org/wiki/Muhammad_ibn_Musa_al-Khwarizmi</a>