If the length of a rectangle is 7 decimeters and the width is 1 decimeter, what is the circumference in decimeters?
一个长方形的长是7分米，宽是1分米，周长是多少分米．
<gadget id="calculator">7 + 1</gadget>
<output>8</output>

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

<result>16</result>