Draw the largest circle inside the square. The circumference of this circle is 12.56 cm. What is the area of this square?
在正方形里面画一个最大的圆，这个圆的周长是12.56厘米，这个正方形的面积是多少．
<gadget id="calculator">12.56 / 3.14</gadget>
<output>4</output>

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

<result>16</result>