rope is used to form a square. The side length of this square is 6.28 meters. If this rope is used to form a circle, what is the area of the circle in square meters?
把一根绳子围成一个正方形，这个正方形的边长是6.28米，如果用这根绳子围成一个圆形，这个圆的面积是多少平方米？
<gadget id="calculator">6.28 * 4</gadget>
<output>25.12</output>

<gadget id="calculator">25.12 / 3.14 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<result>50.24</result>