Arithmetic rope

The calculation rope or knot rope was a common computing resource of the Middle Ages, with the help of which you various mathematical and geometric problems could easily be solved.

As an allegorical personification of the arithmetic in the presentation of the liberal arts was a female character with the attribute of node rope.

A calculation rope generally had at least twelve knots (hence often called Twelve knot cord ) at the same distance. More nodes were specifically for the multiplication and division of advantage.

13 -node cable

In construction of the Middle Ages, the computing rope for architects and builders was indispensable, since it simply equilateral and right-angled triangles and circles can be constructed. To this end, a rope - 13 knots in twelve equal intervals - linked to the first and thirteenth node to a circular ring ( Druid cord). Depending on how many people on which node the closed system stretched from the same units could be ( so ) construct with him on the basis of two fundamental triangles a geometric shape (square, hexagon, octagon, etc.). The ability to specified in some publications, with this line also regular pentagons ( and pentagrams ) construct, is only an approximate solution. Constructive and mathematically it is incorrect.

Arithmetic functions

16 9 = 25 ( Pythagoras )