Towards the end of the Middle Ages, the reckoning masters spared no efforts to teach their fellow citizens how to reckon. Among the best known of these was Adam Riese, whose name is immortalized in the quotation: „According to Adam Riese this makes ....“. Written reckoning as we know it today from our early schooldays was unknown in those days. One worked things out on reckoning tables or reckoning cloths and with the abacus. We will learn about both these methods and will have reckoning competitions. Each child will also make a Roman abacus.