There are a total of 8 birds on the tree, 1 flew away in the first time, and 2 flew away in the second time, how many birds flew away in total.
树上一共有8只小鸟，第一次飞走了1只，第二次又飞走了2只，一共飞走了多少只．
<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<result>3</result>