Chapter 7 - Exponents and Exponential Functions - 7-1 Zero and Negative Exponents - Practice and Problem-Solving Exercises - Page 418: 53

$10^{-3}$

We start with the given expression: $\frac{1}{1000}$ We want to determine what power of $10$ is in the denominator. $1000=10\times10\times10=10^3$ We rewrite the expression as $\frac{1}{10^3}$. The negative exponent rule states that for every nonzero number $a$ and integer $n$, $a^{-n}=\frac{1}{a^n}$. We use this rule to rewrite the expression: $10^{-3}$