rope with a length of 12.86 meters, after wrapping it 10 times around a big tree, there is still 0.3 meters left. What is the diameter of the cross section of this large tree in meters?
一根长12.86米的绳子，把它绕大树10圈后，还剩0.3米．这棵大树的横截面的直径是多少米？
<gadget id="calculator">12.86 - 0.3</gadget>
<output>12.56</output>

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

<result>0.4</result>