To make 200 sections of cylindrical drainage pipes with a length of 2 meters and a cross-sectional diameter of 20 centimeters for a new building, how many square meters of iron sheets are needed?
为一座新楼做200节每节长2米的圆柱形排水管，横截面的直径是20厘米，需要铁皮多少平方米？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">3.14 * (1/5) * 2 * 200</gadget>
<output>251.2</output>

<result>251.2</result>