A square vegetable garden has one side against a wall and is surrounded by a 12-meter-long fence. What is the area of this vegetable field?
一块正方形的菜园，有一面靠墙，用长为12米的篱笆围起来，这块菜地的面积是多少？
<gadget id="calculator">12 / 3</gadget>
<output>4</output>

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

<result>16</result>