The diameter of the front wheel of a road roller is 20 decimeters, and the width is also 20 decimeters. If it turns 20 times per minute, how many square meters of road surface does it press per minute?
一辆压路机的前轮直径是20分米，宽度也是20分米，如果它每分钟转20周，那它每分压过的路面面积是多少平方米？
<gadget id="calculator">20 / 10_000</gadget>
<output>1/500 = around 0.002</output>

<gadget id="calculator">3.14 * 20 * 20 * (1/500)</gadget>
<output>2.512</output>

<result>2.512</result>