Draw the largest circle inside a square, the area is 15.7 square centimeters, then, what is the area of the square in square centimeters?
正一个正方形内画一个最大的圆，面积是15.7平方厘米，那么，正方形的面积多少平方厘米．
<gadget id="calculator">15.7 / 3.14</gadget>
<output>5</output>

<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<result>20</result>