## Algebra 1: Common Core (15th Edition)

$\pi$ is an irrational number.
Rational numbers must be able to have the form of $\frac{x}{y}$, where both x and y are integers, so they have an ending decimal when they are converted to decimal form. However $\pi$, which is 3.1415..., does not have an ending decimal and thus cannot be put into the $\frac{x}{y}$ form.