Answer
$10^{-3}=0.001$
Work Step by Step
From the definition of logarithms,
for $a>0$, $a\neq 1$, and $x > 0$,
$y=\log_{a}x$ means $a^{y}=x$.
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The logarithm with base $10$ is written as log (no base specified).
$-3=\log_{10}(0.001)\ \ $ means $\ \ 10^{-3}=0.001 .$