A rectangular piece of glass is 6 decimeters long and 2 decimeters wide, what is its perimeter?
一块长方形玻璃长是6分米，宽是2分米，它的周长是多少．
<gadget id="calculator">6 + 2</gadget>
<output>8</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<result>16</result>