If the length of a rectangle is 2 decimeters and the width is 2 decimeters, what is its perimeter?
一个长方形的长是2分米，宽是2分米，它的周长是多少分米．
<gadget id="calculator">2 + 2</gadget>
<output>4</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<result>8</result>