Answer
9,000,000 milligrams
Step-by-step explanation
1 kilogram is equivalent to 1,000,000 milligrams. Using this conversion factor, the equivalence of 9 kilograms is found as follows:
[tex]\begin{gathered} 9\text{ kg }=9\text{ kg}{}\cdot\frac{1,000,000\text{ mg}}{1\text{ kg}} \\ \text{ SImplifying the units:} \\ 9\text{ kg }=9\cdot1,000,000\text{ mg} \\ 9\text{ kg}=9,000,000\text{ mg} \end{gathered}[/tex]