A metal ventilation pipe is 3 meters long and 0.2 meters in diameter. To make 5 such ventilation pipes, how many square meters of iron sheet should be used at least?
一条铁皮通风管长3米，直径是0.2米，做5条这样的通风管，至少要用铁皮多少平方米？
<gadget id="calculator">3.14 * 0.2 * 3 * 5</gadget>
<output>9.42</output>

<result>9.42</result>