tellingstavler

Tellingstavler, often translated as "telling tables" or "counting boards," are a type of abacus used in various parts of Europe, particularly in Scandinavia and Germany, from the Middle Ages until the early modern period. They served as a mechanical aid for performing arithmetic calculations.

These devices typically consisted of a flat surface, often a wooden board or a metal plate, marked with parallel lines or columns. Numbers were represented by movable counters, such as pebbles, beads, or metal discs, which were placed on these lines. The position of the counters on the lines indicated their numerical value, usually based on a decimal or duodecimal system. For example, a counter on a specific line might represent ones, while a counter on the next line represented tens, and so on.

Calculations were performed by moving these counters according to specific rules. Addition involved combining counters from different numbers, while subtraction required removing counters. Multiplication and division were typically broken down into a series of additions and subtractions. The user would manipulate the counters on the tellingstavler to arrive at the solution.

Tellingstavler were important tools for merchants, tax collectors, and anyone who needed to perform complex calculations before the widespread adoption of Hindu-Arabic numerals and more advanced calculating devices. Their use declined with the increasing literacy in numerical notation and the eventual development of mechanical calculators. While no longer in common use, they represent an important stage in the history of computation and mathematical tools.