Make 5 chimneys of the same size with iron sheets, each section is 10 decimeters long, and the bottom diameter is 1 decimeter, at least how many m**2 of iron sheets are needed.
用铁皮做5节同样大小的烟囱，每节长10分米，底面直径1分米，至少需要铁皮多少m**2．
<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">3.14 * 1 * 10 * (1/20)</gadget>
<output>1.57</output>

<result>1.57</result>