A rectangular iron sheet with a length of 25.12cm and a width of 18.84cm can be used to make a cylindrical container with the following r= how much cm circular iron sheet.
用一块长为25.12cm，宽为18.84cm的长方形铁皮配上下面r=多少cm圆形铁片正好可以做成圆柱形容器．
<gadget id="calculator">25.12 / 3.14 / 2</gadget>
<output>4</output>

<result>4</result>