A rectangle is 8 meters long and 2 meters wide, what is the circumference in meters?
一个长方形，长是8米，宽是2米，周长是多少米．
<gadget id="calculator">8 + 2</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<result>20</result>