The area of a ring is 12.56 square centimeters. Draw two squares with the diameters of the inner and outer circles of the ring as side lengths. What is the difference in area between the large and small squares?
一个圆环的面积是12.56平方厘米，分别以这个圆环的内、外两个圆的直径为边长画两个正方形．大、小两个正方形的面积相差多少平方厘米．
<gadget id="calculator">12.56 / 3.14</gadget>
<output>4</output>

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

<result>16</result>