In mathematics, a constant is a fixed value that does not change. It can be a number, decimal, fraction, or symbol. Constants are often represented by letters or symbols. Examples of constants include 2, 1.5, $\sqrt{2}$, and $\frac{3}{4}$. In algebra, a constant is a number on its own, or sometimes a letter such as a, b, or c to stand for a fixed number. For example, in the equation "x + 5 = 9", 5 and 9 are constants. A constant term in math is a number, variable, or symbol for an irrational number that has a fixed value.