There are 6 other bus stops between the two bus stops, how many different bus routes are there in these 8 stops?
两个公交车站之间另有6个站，则这8个站中有多少种不同的乘车路线．
<gadget id="calculator">7 + 6 + 5 + 4 + 3 + 2 + 1</gadget>
<output>28</output>

<gadget id="calculator">28 * 2</gadget>
<output>56</output>

<result>56</result>