There is a circular reservoir. Its diameter is 6 meters, what is its approximate footprint?
有一圆形蓄水池．它的直径是6米，它的占地面积约是多少？
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

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

<result>28.26</result>