Use a 25.12dm long iron wire to form a circular iron ring (not counting the interface), what is the diameter of the iron ring in dm.
用一根25.12dm长的铁丝围成一个圆形铁环(接口处不计)，铁环的直径是多少dm．
<gadget id="calculator">25.12 / 3.14</gadget>
<output>8</output>

<result>8</result>