In a rectangle whose length is 9 decimeters and width is 7 decimeters, fold a largest square, what is the area of this square?
在一个长是9分米，宽是7分米的长方形中，折一个最大的正方形，这个正方形的面积是多少．
<gadget id="calculator">7 * 7</gadget>
<output>49</output>

<result>49</result>