# Constant

A constant is a value that does not change. Typically, a constant will be a real number, but can sometimes be written as a variable. When written as a variable, a constant is commonly denoted as c to represent a fixed value.

Example

y = 2x + 3

In the function above, 3 is a constant. The 2 is a fixed number, but it is more appropriate to call it a coefficient because it is multiplied by x.

Example

y = 5

The term "constant" may also refer to a constant function, or a function whose output value is the same for every input value. The function above is a constant function.

Example

π, e, i, etc.

Some constants are given special symbols because they represent significant values and have important applications across different mathematical fields of study.

Related word constant.