The expression you provided appears to be a bit unclear with formatting issues. However, if we are to interpret it, it seems like you are attempting to simplify an expression involving \(10^{-3}\).
Let's clarify and simplify:
\[ 10^{-3} = \frac{1}{10^3} \]
Calculating \(10^3\):
\[ 10^3 = 1000 \]
Thus,
\[ 10^{-3} = \frac{1}{1000} \]
If you were asking about further operations or comparisons with \(-10^3\) or another expression, please clarify, but as it stands, the simplification for \(10^{-3}\) is:
\[ 10^{-3} = \frac{1}{1000} \]
Which can also be expressed as \(0.001\). Let me know if you need further assistance!