Dig a circular pool with a radius of 3 meters. How many square meters does this pool occupy?
挖一个半径是3米的圆形水池，这个水池的占地面积是多少平方米？
<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<result>28.26</result>