Chapter 7 - Exponents and Exponential Functions - 7-2 Scientific Notation - Practice and Problem-Solving Exercises - Page 424: 40

$8\times10^{-3}$

We start with the given expression: $4(2\times10^{-3})$ We rewrite the expression using the associative property: $4\times2\times10^{-3}$ We multiply the first two terms: $8\times10^{-3}$ The number is now in scientific notation, as 8 is between 1 and 10, and -3 is an integer.