There is a circular pool, its circumference is about 31.4 meters, how many square meters does it cover?
有一个圆形水池，它的周长约是31.4米，它的占地面积约是多少平方米？
<gadget id="calculator">31.4 / 3.14 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">3.14 * 25</gadget>
<output>78.5</output>

<result>78.5</result>