koroban

Koroban is a traditional Japanese abacus, also known as the *soroban* in modern usage, though the term "koroban" is more commonly associated with its earlier, simpler forms. The koroban originated in China during the Tang Dynasty (618–907 AD) and was later introduced to Japan, where it evolved into distinct regional variations. Unlike the modern soroban, which features a single bead in the upper deck and four in the lower deck per column, the koroban typically had two beads in the upper deck and five in the lower deck, resembling the Chinese suanpan.

The koroban was widely used in Japan from the Edo period (1603–1868) through the Meiji era (1868–1912) as a primary tool for arithmetic calculations. It was particularly valued in business, education, and daily life due to its efficiency in performing complex calculations quickly. The device consists of a frame with vertical rods, each containing beads that can be moved to represent numbers. Users manipulate the beads using their thumbs and fingers, sliding them up or down to perform addition, subtraction, multiplication, and division.

The koroban played a significant role in Japan’s mathematical education system, with many schools teaching abacus techniques alongside traditional arithmetic. Its use declined in the mid-20th century with the rise of electronic calculators, though it remains a cultural and historical artifact. Today, the koroban is studied for its historical importance and as part of Japan’s cultural heritage, reflecting the country’s long-standing relationship with manual calculation tools. Some enthusiasts and educators continue to practice koroban arithmetic as a cognitive exercise or for its educational benefits in improving mental math skills.