The circumference of the bottom surface of the roller of the road roller is 12.56m, and the length is 1.2m. The roller rolls 10 times per minute. How many square meters of road surface is rolled in half an hour?
压路机滚筒的底面周长是12.56m，长是1.2m，压路机每分钟滚动10周，半小时压过的路面是多少平方米？
<gadget id="calculator">12.56 * 1.2</gadget>
<output>15.072</output>

<gadget id="calculator">10 * 30</gadget>
<output>300</output>

<gadget id="calculator">15.072 * 300</gadget>
<output>4_521.6</output>

<result>4_521.6</result>