If a 10-meter-long copper wire is wound 3 times on a disc and there is 0.58 meters left, what is the radius of the disc in meters?
若10米长的铜丝，在一个圆盘上绕了3圈还剩0.58米，这个圆盘的半径是多少米．
<gadget id="calculator">10 - 0.58</gadget>
<output>9.42</output>

<gadget id="calculator">9.42 / 3 / 3.14 / 2</gadget>
<output>0.5</output>

<result>0.5</result>