The length of a bus card is 4 cm, which is twice the width, so what is the circumference of the bus card?
一公交卡长为4厘米，是宽的2倍，那么此公交卡周长是多少？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">4 + 2</gadget>
<output>6</output>

<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<result>12</result>