The front wheel of a road roller is a cylinder with a cross-sectional diameter of 2m and a length of 4m. How many m**2 can be rolled for one week?
一种压路机的前轮是一个圆柱，它的横截面直径是2m，长4m．滚动一周，能压路多少m**2？
<gadget id="calculator">3.14 * 2 * 4</gadget>
<output>25.12</output>

<result>25.12</result>