A paint roller brush is 30 cm long and 8 cm in diameter. What is the area in square centimeters when it rolls in one circle?
涂料滚筒刷长30厘米，直径是8厘米，滚动一圈的面积是多少平方厘米．
<gadget id="calculator">3.14 * 8 * 30</gadget>
<output>753.6</output>

<result>753.6</result>