Quantity, weight, shape, area, etc. When buying goods in the market, we will choose the quantity to buy and calculate the price to weigh the goods. The area of each booth is different, and the shape of the goods is also different. There are mathematical elements such as rectangle, circle and ellipse, so there are mathematical elements such as quantity, weight, shape and area on the market. Mathematical elements refer to the basic units that can be used to construct mathematical structures, such as points, lines, surfaces and bodies.