A book has 100 pages and can be read in two days. I read the whole book (2/5) on the first day, how many pages did I start from on the second day?
一本书有100页，两天读完．第一天读了全书的(2/5)，第二天从多少页读起的．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">100 * (2/5)</gadget>
<output>40</output>

<gadget id="calculator">40 + 1</gadget>
<output>41</output>

<result>41</result>