The diameter of the front wheel of a road roller is 1m, the width of the wheel is 2m, and it rolls 15 times per minute when it is working.
一台压路机前轮直径1m，轮宽2m，工作时每分钟滚动15周，这台压路机工作半小时前轮压过的路面是多少平方米？
<gadget id="calculator">3.14 * 1 * 15 * 30</gadget>
<output>1_413</output>

<gadget id="calculator">1_413 * 2</gadget>
<output>2_826</output>

<result>2_826</result>