The roller of a road roller is 1.2 meters long and 1 meter in diameter. If it rotates 20 times, how many square meters of road surface will it pass?
一台压路机的滚筒长为1.2米，直径为1米，如果它转了20圈，压过的路面是多少平方米．
<gadget id="calculator">3.14 * 1 * 1.2 * 20</gadget>
<output>75.36</output>

<result>75.36</result>