The length of a rope around a circular cement column is 12.56 decimeters. How many square decimeters does this concrete column occupy?
一根绳子绕圆形水泥柱一周的长是12.56分米．这根水泥柱的占地面积是多少平方分米？
<gadget id="calculator">12.56 / 3.14 / 2</gadget>
<output>2</output>

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

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

<result>12.56</result>