Uncle Li has surrounded a square field with a 40-meter-long fence. What is the area of the land in square meters?
李叔叔用长40米的篱笆围了一块正方形地，这块地的面积是多少平方米？
<gadget id="calculator">40 / 4</gadget>
<output>10</output>

<gadget id="calculator">10 * 10</gadget>
<output>100</output>

<result>100</result>