Among the 11 students, there are one principal and one vice-monitor. Now select 3 students to participate in the shot put, long jump and long-distance running competitions. If there is at least one principal and one vice-monitor, how many different selection methods are there?
在11名学生中，有正、副班长各一名，现选派3人分别参加铅球、跳远、长跑比赛，如果正、副班长至少有一人在内，则有多少种不同的选法．
<gadget id="calculator">9 ** 1</gadget>
<output>9</output>

<gadget id="calculator">72 + 9</gadget>
<output>81</output>

<result>81</result>