A square handkerchief has a perimeter of 8 decimeters, what is its area?
一张正方形的手帕，周长是8分米，面积是多少平方分米？
<gadget id="calculator">8 / 4</gadget>
<output>2</output>

<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<result>4</result>