If the side length of a square is 25dm, what is its perimeter in meters?
一个正方形的边长是25dm，它的周长是多少米．
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">25 * (2/5)</gadget>
<output>10</output>

<result>10</result>