Use a 10-meter-long rope to wrap 4 times around a tree, leaving 3.72 meters. What is the diameter of this tree in meters?
用一根长是10米的绳子围着一根树绕4圈，还余3.72米．这棵树的直径是多少米？
<gadget id="calculator">10 - 3.72</gadget>
<output>6.28</output>

<gadget id="calculator">6.28 / 4 / 3.14</gadget>
<output>0.5</output>

<result>0.5</result>