The rectangle is 6 decimeters long and 4 decimeters wide. How many decimeters is the circumference.
长方形长6分米，宽4分米．周长多少分米．
<gadget id="calculator">6 + 4</gadget>
<output>10</output>

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

<result>20</result>