Divide the 19 exercise books on average to how many students, each person will get 2 books, and there will be 1 book left.
把19本练习本平均分给多少个同学，每人分到2本，还余1本．
<gadget id="calculator">19 - 1</gadget>
<output>18</output>

<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<result>9</result>