This sketch of Gerbert de Aurillac's checker board shows the use of "Arabian numbers" on a checker board with 2x3 decimal positions (labelled in Roman numerals on top). The Indian numerals appear in various orientations.
To perform calculations with the new "Arabic" tokens the calculation has to be done mentally first, and the result has to be entered by taking some tokens off and replacing them by others.
Ifrah, G. (2000) Universal History of Numbers. John Wiley & Sons. Translated from Ifrah, G. (1981) Histoire Universelle des Chiffres, (Seghers).
Image: © M. Tomczak, adapted from Ifrah (2000); Creative Commons license