In elementary mathematics, a variable is an alphabetic character representing a number, called the *value* of the variable, that is arbitrary, not fully specified, or unknown.

Variables are useful for several reasons.

# Unknown Values

Variables can represent numbers whose values are not yet known.
For example, if the temperature of the current day,

# General Formulas

## Varying Quantities

Variables may describe mathematical relationships between quantities that vary. For example, the relationship between the circumference,

Variables may also describe general problems without specifying the values of the quantities involved. For example, it can be stated specifically that 5 minutes is equivalent to

## Mathematical Properties

Variables may describe some mathematical properties. For example, a basic property of addition is commutativity, which states that the order of numbers being added together does not matter. Commutativity is stated algebraically as

# Types of Variables

Variables can be used to represent different types of numbers. It is common that many variables appear in the same mathematical formula, and they may play different roles. Some names or qualifiers have been introduced to distinguish them.

For example, in the general cubic equation
*parameters *of the equation. The last one, *unknown*, and the variables that are multiplied by *coefficients*. In this equation, the coefficients are *constant*; in this case,

Note that a *term* of an equation is any value (variable or number) or expression that is separated from another term by a space or a character (such as "

Note that unknown variables are often denoted by

In this case,