abacuses

An abacus is a calculating device consisting of a rectangular frame holding a number of rods, each rod strung with beads that can slide freely. Beads are moved toward a dividing bar on the rod to represent digits; the position of beads encodes numbers and allows arithmetic operations. Abaci have been used for centuries in many cultures and continue to be employed as educational tools and in some regions for practical calculation.

The concept predates written numerals in many places. Counting boards and early bead frames appear in ancient Mesopotamia and China, and the word abacus derives from Latin and Greek terms for a counting board. Distinct regional variants developed, including the Chinese suanpan with two beads on the upper deck and five on the lower deck per rod, and the Japanese soroban, which typically uses one bead above and four below per rod. The Russian schoty uses a different layout with ten beads per wire, read from left to right.

Construction varies, but most devices feature a frame, a set of rods, and one or more sections of beads. They are operated by finger movement and may require rules for carries and borrows during calculation. Abaci support basic arithmetic and, with practice, more complex operations such as multiplication, division, and square roots.

Today calculators are common, but abaci are still taught in some schools, used by merchants in certain markets, and maintained by enthusiasts. Portable versions and digital simulations preserve traditional counting methods while linking them to modern numeracy.