To find the area of a circle, you can use the formula:
\[ \text{Area} = \pi r^2 \]
where \( r \) is the radius of the circle. The diameter of the circle is given as 10 millimeters, so the radius \( r \) is half of the diameter:
\[ r = \frac{10}{2} = 5 \text{ mm} \]
Now, substituting the radius into the area formula with \( \pi \approx 3.14 \):
\[ \text{Area} = 3.14 \times (5)^2 = 3.14 \times 25 \]
Calculating that:
\[ 3.14 \times 25 = 78.5 \]
Therefore, the area of the circle is approximately \( 78.5 \) square millimeters when estimated to the tenths place.