A story book has 160 pages, and 40% of it has been read, how many pages have been read.
一本故事书有160页，已经看了它的40%，看了多少页．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">160 * (2/5)</gadget>
<output>64</output>

<result>64</result>