Fourth, there are four beads under the gear, fifth, there is a bead on the gear, sixth, there is a bead on the gear, there is a bead on the gear, and there are two beads on the gear.

The top is divided into 10 digits, the bottom is 1000 digits, and so on. , the last number, the last number and so on.

Abacus is an auxiliary tool for manual operation and calculation. It originated in China and has a history of more than 2,600 years. This is an important invention in ancient China. Before Arabic numerals appeared, abacus was a widely used computing tool in the world. Now, abacus continues to be used in parts of Asia and the Middle East, especially in shops, which can be bought from shops that supply goods from China and Japan. In the west, it is sometimes used to help children understand numbers. Some mathematicians like to experience the feeling of calculating simple arithmetic problems with an abacus.