The bottom of a granary is a circle with a diameter of 6 meters. What is the area of the granary in square meters?
一个粮仓的底面是直径为6米的圆，这个粮仓占地面积是多少平方米？
<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>