A cylindrical granary has a length of 12.56 meters around the granary, so how many square meters does the granary occupy?
一个圆柱形的粮仓，绕粮仓走一周的长度为12.56米，那么这个粮仓的占地面积是多少平方米？
<gadget id="calculator">12.56 / 3.14 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">4 * 3.14</gadget>
<output>12.56</output>

<result>12.56</result>