Uncle Zhang used a 24-meter-long fence to form a rectangular vegetable field with the largest area in the yard by leaning against a wall. Calculate its area in square meters?
张大伯用24米长的篱笆，在院子里用一面靠墙的方法，围成了一块面积最大长方形菜地，算一算它的面积是多少平方米？
<gadget id="calculator">12 * 6</gadget>
<output>72</output>

<result>72</result>