Abacus

Abacus is a form of Technology and Culture.

Description
An abacus is a most marvelous device for adding calculation. It consists of columns of beads in a frame divided into two parts. Most commonly, each column has two beads in the upper part, and four in the lower. Numbers are added by moving up beads in the lower part, until all are used when a bead in the upper part is moved. When the upper beads have both been moved, that column is reset, and a bead in the next column is moved.

Effects

 * Value of trade increased by 15%