Try the following GMAT Problem Solving question on how to turn a decimal product to a whole number.
Question 56:
What is the least integer value of $n$ for which the product $(0.004)(0.015)(0.0025)(10^n)$ is an integer ?

$\quad 10$

$\quad 8$

$\quad 0$

$\quad 8$

$\quad 10$