算盘的发明 The invention of Abacus

Abacus es in you tie a knot, when money goes out you undo a knot. After that, Confucius developed it into balls on poles with a frame around and the ancient abacus came into being at that moment.

From then on, the whole world started using it for calculation. And it is used by many people even now. There are also some people who collect old abacus because abacus has a long history and is very famous in the world.