To make 10 cylindrical ventilation pipes with a length of 1.5 meters and a circumference of 0.6 meters at the bottom, at least how many square meters of iron sheets are needed.
做10节长1.5米，底面周长0.6米的圆柱形通风管，至少需要多少平方米的铁皮．
<gadget id="calculator">0.6 * 1.5 * 10</gadget>
<output>9</output>

<result>9</result>