If the circumference of a round cup cover is 18.84 cm, what is the area of the cup cover?
一圆形杯盖周长为18.84厘米，则这个杯盖的面积是多少．
<gadget id="calculator">18.84 / 2 / 3.14</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<result>28.26</result>