A circular cistern has a circumference of 31.4 meters, what is its floor area in square meters
一个圆形的蓄水池，它的周长31.4米，它的占地面积是多少平方米
<gadget id="calculator">31.4 / 2 / 3.14</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>