Four 2 Election class committee, the students have to choose 2 out of 10 students to serve as the principal and deputy squad leader, how many different election methods are there?
四2竞选班委，同学们要在10个同学中选2人担任正、副班长，有多少种不同的选法．
<gadget id="calculator">10 - 1</gadget>
<output>9</output>

<gadget id="calculator">10 * 9</gadget>
<output>90</output>

<result>90</result>