The side length of a square is 6 cm, what is its perimeter in dm.
正方形的边长是6cm，它的周长是多少dm．
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">6 * (2/5)</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>