Use iron sheets to make 10 cylindrical ventilation pipes, each section is 9dm long, and the circumference of the bottom surface is 12.56dm, at least how much dm of iron sheet is needed**2.
用铁皮制作圆柱形的通风管10节，每节长9dm，底面周长是12.56dm，至少需要铁皮多少dm**2．
<gadget id="calculator">12.56 * 9 * 10</gadget>
<output>1_130.4</output>

<result>1_130.4</result>