A non-terminating but recurring decimal is

Real numbers expressed as non-terminating but recurring (repeating) decimals can always be converted into the fraction form $\frac{p}{q}$, where $p$ and $q$ are integers and $q\ne 0$. Therefore, they are classified as rational numbers (e.g., $\mathrm{0.333...}=\frac{1}{3}$).