Computing tools widely used in the world. The abacus is rectangular, surrounded by a wooden frame with small sticks fixed in it. Wooden sticks are covered with wooden beads, and a beam in the middle and an abacus are divided into two parts. There are two beads in the upper part of each stick, five for each bead, and five for the lower part, one for each bead. Abacus is called abacus, and abacus has corresponding rules for four operations, which are collectively called abacus rules. With the use of abacus, people have summed up many formulas to make the calculation faster. Compared with general operation, skilled abacus calculation is not inferior to calculator, especially addition and subtraction. When in use, you can dial the abacus up and down according to the formula to calculate. Abacus calculation is simple and quick. Before calculators and computers became popular, they were widely used in shops in China. In ancient times, people used small sticks to calculate. These sticks are called "computing chips", and calculations with computing chips as tools are called "calculations". Later, with the development of production, the calculation with wooden sticks was limited, so people invented a more advanced calculation tool-abacus. By the Ming Dynasty, abacus could not only add, subtract, multiply and divide, but also calculate the land area and the size of things of various shapes. Because the abacus is simple to make, cheap, easy to remember and calculate, it is widely used in China and spread to Japan, North Korea, the United States and Southeast Asia. Now, it has entered the era of electronic computers, but the ancient abacus still plays a certain role. In China, there are a group of abacus experts in all walks of life. The use of abacus is not only convenient to operate, but also has the function of exercising thinking ability, because abacus needs the close cooperation of brain, eyes and hands, and it is a good way to exercise the brain.