Answer
$3\;ft^2=432\; in^2$.
Work Step by Step
Conversion factor is
$=\frac{144\; in^2}{1\; ft^2}$
The given unit of measure is
$=3\;ft^2$
Multiply by the conversion factor.
$=3\;ft^2\cdot \frac{144\; in^2}{1\; ft^2}$
Simplify.
$=432\; in^2$.