Answer
$1.5g/cm^{2}=15mg/mm^{2}$
Work Step by Step
We need to convert grams per square centimeter into milligrams per square millimeters.
The conversion factors are:
$1 g=1000mg$ and $1cm^{2}=100mm^{2}$
So,
$1.5g/cm^{2}*\frac{1000mg}{1 g}*\frac{1cm^{2}}{100mm^{2}}=15mg/mm^{2}$
