Answer
$$\frac{a}{9 } $$
Work Step by Step
Let $$x= 0.aaaaaaaaaaaaaa\cdots $$
Then
\begin{align*}
10x-x&= a.aaaaaaaaa\cdots-0.aaaaaaaaaa\cdots \\
9x&=a\\
x&=\frac{a}{9 }
\end{align*}
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.