Answer:
[tex]\large \boxed{\text{ 20 mm}^{2}}[/tex]
Explanation:
In multiplication and division problems, your answer can have no more significant figures than the number with the fewest significant figures.
[tex]\text{3.2 mm} \times \text{5 mm} = \text{16 mm}^{2}[/tex]
There are two significant figures in 3.2 and one in 5.
[tex]\text{You must round to one significant figure and report the answer as $\large \boxed{\textbf{ 20 mm}^{\mathbf{2}}}$}[/tex]
