A 36-meter-long fence is placed around a square vegetable field. What is the area of this vegetable field in square meters?
一块正方形菜地四周围上了长36米的篱笆，这块菜地的面积是多少平方米？
<gadget id="calculator">36 / 4</gadget>
<output>9</output>

<gadget id="calculator">9 * 9</gadget>
<output>81</output>

<result>81</result>