A 2-meter-long cuboid downpipe has a cross-section of a square with a side length of 8 cm. How many square centimeters of iron sheet is needed to make this downpipe?
一根2米长的长方体落水管，横截面是边长为8厘米的正方形，做这个落水管至少需要多少平方厘米的铁皮．
<gadget id="calculator">2 * 100</gadget>
<output>200</output>

<gadget id="calculator">8 * 4 * 200</gadget>
<output>6_400</output>

<result>6_400</result>