Make 10 cylindrical ventilation pipes, the circumference of the bottom surface is 40 cm, and the length is 1.5 m. How many square meters of iron sheet is needed at least?
做10节圆柱形通风管，底面周长是40厘米，长1.5米．至少需要铁皮多少平方米？
<gadget id="calculator">10 / 10_000</gadget>
<output>1/1_000 = around 0.001</output>

<gadget id="calculator">40 * 1.5 * 100 * (1/1_000)</gadget>
<output>6</output>

<result>6</result>