A cuboid ventilation pipe is 3m long, and the bottom surface is a square with a side length of 3dm. How much iron sheet is needed to make this ventilation pipe.
一个长方体通风管长3m，底面是边长3dm的正方形，做这个通风管需多少铁皮．
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(3/10) * 4 * 3</gadget>
<output>18/5 = around 3.6</output>

<result>18/5 = around 3.6</result>