Rectangle: ab

Trapezoid: (a+b)h divided by 2

Square: axa

Approximation: number, also known as factor. The quotient (b≠0) obtained by dividing the integer A by the integer B is exactly an integer without remainder, so we say that A can be divisible by B or B can be divisible by A. A is called a multiple of B, and B is called a divisor. Before college, the word "divisor" was generally limited to positive divisor. Both divisor and multiple are concepts of binary relationship, and an integer cannot be said to be a divisor or multiple in isolation. The divisor of an integer is finite. At the same time, it can be a common divisor under certain circumstances.