There are still 5 stops between A and B, so how many kinds of tickets do you need to prepare for the train from A to B?
甲乙两站之间还有5个停靠点，那么火车从甲地到乙地共需准备多少种车票．
<gadget id="calculator">6 + 5 + 4 + 3 + 2 + 1</gadget>
<output>21</output>

<result>21</result>