The front wheel of a road roller is cylindrical, with a width of 4 meters and a diameter of 1 meter. It rolls 4 times per minute. How many square meters of road surface does it pass?
一台压路机的前轮是圆柱形状的，轮宽4米，直径是1米，每分钟滚动4周，压过的路面是多少平方米？
<gadget id="calculator">3.14 * 4 * 1 * 4</gadget>
<output>50.24</output>

<result>50.24</result>