The number of division operations in arithmetic is called quotient, which comes from the decimal places of missing arrows, and its meaning comes from the fact that the decimal places of missing arrows are constant. Business has the significance of measurement and negotiation. The buying and selling relationship between people should follow the principle of equivalent exchange, and both sides of the exchange should measure whether the value of each other's goods is equivalent to that of their own goods. Therefore, commerce is also used as commerce, commodities and businessmen, which is still an extension of the scale of missing arrows.