To cut a circular paper with a circumference of 12.56 decimeters, at least how many square decimeters of paper are needed.
要剪一个周长是12.56分米的圆形纸片，至少需要多少平方分米的正方形纸片．
<gadget id="calculator">12.56 / 3.14</gadget>
<output>4</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<result>16</result>