Absolute value, like addition, subtraction, multiplication and division, is an operation, and the operation symbol is usually represented by ||. The significance of this operation is that the absolute value of positive numbers and 0 is itself, and the absolute value of negative numbers is its inverse. In short, the absolute value of a number is negative.

Represented by algebraic expression as:

| a | = a(a & gt； 0)

| a | =-a(a & lt； 0)

|a|=0(a=0)

On the number axis, the absolute value of a number is expressed as the distance from the point representing this number to the origin. For example, |-5| represents the distance between the point representing -5 on the number axis and the origin, that is |-5|=5.