Select 3 class leaders from 4 boys and 2 girls, and at least one of them is a girl. How many ways are there?
从4名男生和2名女生中选出班干部3人，其中至少有一名女生，共有多少种选法．
<gadget id="calculator">2 * 6</gadget>
<output>12</output>

<gadget id="calculator">1 * 4</gadget>
<output>4</output>

<gadget id="calculator">12 + 4</gadget>
<output>16</output>

<result>16</result>