Abacus is a digital calculation method with abacus as a tool, which is known as the fifth invention in China, and has been with China people for over 800 years.

It is known as "the oldest computer in the world" with its simple calculation tools and unique mathematical connotation. With the development of computer technology, the calculation function of abacus is gradually weakened, but the ancient abacus still has tenacious vitality.

The abacus is a simple calculation tool invented by China people. The word "abacus calculation" was first seen in Xu Yue's Notes on Numerology written in the Han Dynasty, and there is a saying: "abacus calculation, control of four seasons, latitude and longitude three talents". Now it is said that abacus has a history of more than 1800 years, and it should be calculated according to this time point. But the abacus method at that time was still very different from today.

Abacus structure

In the traditional sense, the abacus consists of five beads, the upper one stands for "5" and the lower one stands for "1". When calculating with an abacus, the five-liter decimal system is adopted, that is, when each gear is "5", it is represented by a bead, and when each gear is "10", it will advance to the previous gear. Accordingly, four beads are enough for each gear.

One of the reasons is that China used "16 two systems" to calculate the weight in ancient times, that is, one catty equals sixteen taels. Modern people often say that two people are almost as bad, which means they are the same as each other. But half a catty is half a catty, and eight liang is eight liang. How can it be equal? It turns out that in the ancient weight unit system, one catty was equal to sixteen taels, so half a catty was equal to eight taels.

Every gear can be counted as "15", so "16" will advance to the next gear. Therefore, the traditional abacus calculation of "upper two and lower five balls" in China is formed to adapt to hexadecimal.

The second reason is that the ancient multiplication used "leaving the head to multiply". The first bead was not enough, and the second bead was necessary. Influenced by long-term habits, some accountants still like to use the abacus with two beads and five beads, but at home and abroad, they use the abacus with four beads.