Calculation box
A calculation box is an arithmetic aid that was used particularly in elementary schools. It consists of small wooden blocks that are of different lengths depending on their numerical value and are marked with different colors. By placing several bars next to or on top of each other, you can add, subtract or multiply, for example. A typical box of this type is about 12 x 12 x 1.5 cm. There were similar aids for set theory : colored geometric figures such as circles, squares, triangles and T-, S- and L-shaped parts.
Illustration: On the picture on the right you can see cuboids of length 2 to 10 (colored). If you take the bottom bar as an example, the calculation 3 + 3 + 3 + 1 = 10 is shown in orange and yellow above. The calculation 2 + 2 + 2 + 2 + 2 = 10 can be seen in shades of blue on the side. The invoices 5 + 5 and 4 + 4 + 2 are shown on the opposite sides. The color scheme is the same for all bars and thus presents parts of the multiplication table . You can subtract by placing natural-colored blocks of various lengths that fill the other half of the box. Simple multiplications such as 5x2 = 10 can also be carried out or calculated with these.
Another type of calculation box was invented in the 17th century by Caspar Schott , who in 1668 described a "mathematical shrine" in the Organum Mathematicum , which also included such a box. Inside such a calculation box there are ten horizontally rotating cylinders similar to the calculators of Lord John Napier (1550 to 1617). With these bars, which are based on a different principle, you can also multiply and divide very large numbers.