To make a 20-meter ventilation pipe, the pipe joint is square, and the side length is 0.4 meters. How many square meters of iron sheets are needed to make this pipe? (not counting seams)
做一个20米的通风管，管道接口是正方形，边长0.4米，做这个管道至少需要用铁皮多少平方米？(接缝处不计)
<gadget id="calculator">0.4 * 4 * 20</gadget>
<output>32</output>

<result>32</result>