What is the origin of 20-character abacus?

The origin of abacus can be traced back to 600 BC. It is said that there was a "computing board" in China at that time. The ancients strung 10 abacus beads into a group, arranged them in groups, put them in boxes, and then quickly set aside the abacus beads for calculation.

However, according to public information, the word "abacus calculation" was first seen in the Notes on Numerology written by Xu Yue in the Eastern Han Dynasty. Among them, there is a cloud: "The abacus controls the four seasons, and the latitude and longitude are three talents." Zhen Luan of the Northern Zhou Dynasty made an annotation to this effect, to the effect that the board was carved into three parts, the upper and lower parts were used to block the beads and the middle part was used to locate them. Each person has five beads, and the upper bead and the lower four beads are distinguished by color, which is later called "file". There are five beads on the top and one on the bottom.

The shape of an abacus

In ancient times, our abacus in China was varied, with different shapes and materials. The earliest materials were wood, bamboo, copper, iron, jade and ivory.

The earliest visible abacus image in China comes from the abacus in The Riverside Scene at Qingming Festival by Zhang Zeduan in the Northern Song Dynasty. Similar to the modern abacus, it is a fifteen-file and fourteen-file abacus, with five pearls on the top and one pearl on the bottom. This calculation tool saves space and has fast operation speed. Remember that "three times, five times, two times" and so on can do a lot of paperwork, so it is rapidly popularized among the people.

At the beginning of the invention, China's abacus used diamond beads, which were changed to round beads in the Ming Dynasty. The top two beads are five, and the bottom five beads are one. Each file represents 0 to 15 numbers, which has become a universal computing tool for hexadecimal and decimal systems. At that time, the main weight was one kilogram equal to sixteen taels. Therefore, as long as the cloth shop uses one upper bead and four lower beads, the grain shop needs all seven beads for abacus. Such an abacus can be used for addition, subtraction, multiplication and division.