If the perimeter of a square is 0.4 meters, what is the area in square meters?
一个正方形周长是0.4米，面积是多少平方米．
<gadget id="calculator">0.4 / 4</gadget>
<output>0.1</output>

<gadget id="calculator">0.1 * 0.1</gadget>
<output>0.01</output>

<result>0.01</result>