How to Use an Abacus
Before I begin describing how to use an abacus, I ought to specify that there really is not just one, quintessential abacus. In general, there are three types of abaci: dust, counter, and frame. (These categories are suggested in passing by Gardner, Smith, and Williams, but I would like to establish them formally in my final paper.) The dust abacus was a dustboard (defined in post) with columns for place value marked, and Hindu numerals (excluding zero) written in these columns (Ifrah, 2000). This method is only a few steps from the modern pen-and-paper method.