A circular piece of plastic has a radius of 9 decimeters, what is its area in square decimeters?
一块圆形塑料片的半径是9分米，它的面积是多少平方分米？
<gadget id="calculator">9 ** 2</gadget>
<output>81</output>

<gadget id="calculator">3.14 * 81</gadget>
<output>254.34</output>

<result>254.34</result>