The formula of multiplicand × multiplier = product is correct. Multiplication follows the law of exchange. When two numbers are multiplied, the position of the exchange factor remains unchanged. If the dependent variable f and the independent variables x 1, x2, x3, ... ….xn are qualitatively different from each independent variable, it will lose its meaning without any independent variable f, which is called multiplication.
For example:
1、 1×2=2;
2、3×4= 12;
3、5×5=25;
4、85× 15= 1275;
5、85×28=2380;
6、43×66=2838;
7、58×36=2088;
8、87×58=5046。