A book has 50 pages. If you are naughty, you read the whole book (2/5) on the first day. How many pages should you read on the second day?
一本书有50页，淘气第一天看了全书的(2/5)，第二天应从第多少页看起．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">50 * (2/5)</gadget>
<output>20</output>

<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<result>21</result>