There is a circular fountain on the square, and its circumference is measured to be 31.4m. What is the floor area of this fountain in m**2?
广场上有一个圆形喷泉，量得它的周长是31.4m，这个喷泉的占地面积是多少m**2？
<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>