Li Xiang and Zhou Ming used a 13m long rope to wrap around a big tree 10 times, leaving 0.44m left. What is the approximate diameter of the cross-sectional area of the trunk of this big tree?
李香和周明用一根长为13m的绳子绕一颗大树围了10圈还余0.44m，这棵大树树干的横截面积直径大约是多少米？
<gadget id="calculator">13 - 0.44</gadget>
<output>12.56</output>

<gadget id="calculator">12.56 / 10 / 3.14</gadget>
<output>0.4</output>

<result>0.4</result>