Is 0 recurring allowed in repeating decimals? After a question in Puzzling SE and not being able to find anything which answers this: Is zero recurring allowed in repeating/recurring decimals? So can I write something like: $$5 = 5.\overline{0}$$ or even: $$4.\overline{9} = 5.\overline{0}$$ If it isn't, then would this mean that $0$ is the only rational number which cannot be written as a repeating decimal?

Yes. Furthermore, it's convenient to assume that _all_ places in a decimal are filled, so any terminating decimal notation implicitly means to fill the unmarked positions with zeros.

That is, by $1.5$, we really mean $\bar{0}1.5\bar{0}$.