Constant is a fixed value. For example, the ratio of the circumference to the diameter of a circle is π, and the expansion coefficient of iron is 0.0000 12. Constant is a name with a certain meaning, which is used to replace numbers or strings, and its value never changes. In mathematics, the capital letter "c" is usually used to represent a constant.

In physics, many measured values are called constants. For example, the coefficient of universal gravitation and the acceleration of surface gravity. However, some studies show that some of these constants are not constants, so they are called "indefinite constants" and "non-constant constants".

Extended data antonym concept: variable

In elementary mathematics, variables or independent variables are symbols used to represent a value, which can be arbitrary, unspecified or undetermined. In algebraic operation, many problems can be solved in one operation when variables are replaced by certain numerical values.

A typical example is the unary quadratic formula. By substituting the coefficients of the equation into the variables in the formula, the value of each unary quadratic equation can be solved.

Variables are usually represented by an English letter. If you use more than one English letter, it is easy to be confused as multiplication of two variables. I, n, m, x, y and z are common variable names, where n, m and z often represent integers, and I often represent increasing variables in a loop (for example, in a sorting algorithm).