rope 8m long is wrapped around a big tree and there is still 1.72m left. What is the circumference of the big tree in m?
用一根长8m的绳子绕一棵大树一圈后还剩1.72m，这棵大树的周长是多少m．
<gadget id="calculator">8 - 1.72</gadget>
<output>6.28</output>

<result>6.28</result>