If you read (1/7) of a book every day, how many days can you finish it.
一本书，每天看它的(1/7)，多少天可以看完．
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">1 / (1/7)</gadget>
<output>7</output>

<result>7</result>