The circumference of the bottom of a circular fountain is 15.7 meters. How many square meters does this fountain occupy?
一个圆形喷水池的底面周长是15.7米，这个喷水池占地多少平方米？
<gadget id="calculator">15.7 / 3.14 / 2</gadget>
<output>2.5</output>

<gadget id="calculator">2.5 ** 2</gadget>
<output>6.25</output>

<gadget id="calculator">3.14 * 6.25</gadget>
<output>19.625</output>

<result>19.625</result>