In order to solve this problem, we can use a very simple trick.
First, let's set \(x = 0.\overline{2123}\)
If we have this for the value of x, we get \(10000 x = 2123.\overline{2123}\)
Now, we subtract x from 10000x. Note that the repeating parts get canceled out. We get
\(10000x-x= 2123.\overline{2123} -\overline{2123}\\ 9999x=2123\)
This means we get
\(x = \frac{2123}{9999}\)
Simplifying, we get
\(x = \frac{193}{909}\)
So our final answer is \( \frac{193}{909}\)
Thanks! :)