A book has a total of 200 pages, I read 20 pages, and I haven't read the rest.
一本书共200页，看了20页，还剩多少没有看．
<gadget id="calculator">200 - 20</gadget>
<output>180</output>

<gadget id="calculator">180 / 200</gadget>
<output>9/10 = around 0.9</output>

<result>9/10 = around 0.9</result>