Uncle Wang used a 12-meter-long fence to surround the city with a rectangular sheepfold against the wall. What is the largest area of the sheepfold?
王大叔用12米长的篱笆围城一面靠墙的长方形羊圈．这个羊圈面积最大是多少？
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

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

<result>16</result>