It is known that the area of a quarter circle is 6.28 square meters, what is the area of this circle in square meters?
已知一个四分之一圆的面积是6.28平方米，这个圆的面积是多少平方米．
<gadget id="calculator">6.28 * 4</gadget>
<output>25.12</output>

<result>25.12</result>