If a square with a side length of 5dm is enlarged by 4:1, what is the area of the figure obtained in square decimeters?
一个边长是5dm的正方形，按4：1放大，得到的图形的面积是多少平方分米．
<gadget id="calculator">5 * 4</gadget>
<output>20</output>

<gadget id="calculator">20 * 20</gadget>
<output>400</output>

<result>400</result>