A 12.96-meter rope is wrapped 10 times around the tree and its length is 0.4 meters. What is the area of the cross-section of the trunk?
一根12.96米的绳子，绕树10圈还长0.4米，求树干横截面的面积？
<gadget id="calculator">12.96 - 0.4</gadget>
<output>12.56</output>

<gadget id="calculator">12.56 / 10</gadget>
<output>1.256</output>

<gadget id="calculator">1.256 / 3.14 / 2</gadget>
<output>0.2</output>

<gadget id="calculator">0.2 ** 2</gadget>
<output>0.04</output>

<gadget id="calculator">3.14 * 0.04</gadget>
<output>0.1256</output>

<result>0.1256</result>