A cement factory needs to make 10 cuboid metal ventilation pipes, the mouth of which is a square with a side length of 30 cm, and the length of the pipe is 2 meters. How many square meters of iron sheet are needed?
水泥厂要制作10根长方体铁皮通风管，管口是边长30厘米的正方形，管子长2米．共需多少平方米铁皮？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(3/10) * 4 * 2 * 10</gadget>
<output>24</output>

<result>24</result>