There are 8 lights in the classroom, all of them are on, and now 6 lights are turned off, how many lights are there in the classroom?
教室里8盏灯，全部亮着，现在关掉了6盏灯，教室里还有多少盏灯．
<gadget id="calculator">8 - 6</gadget>
<output>2</output>

<result>2</result>