Xiaogang reads a book and finishes it in three days. I read the whole book on the first day (7/18), and read the whole book on the second day (4/9). How much of the whole book did you read on the third day?
小刚看一本书，三天看完．第一天看了全书的(7/18)，第二天看了全书的(4/9)．第三天看了全书的几分之几？
<gadget id="calculator">7 / 18</gadget>
<output>7/18 = around 0.388889</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">1 - (7/18) - (4/9)</gadget>
<output>1/6 = around 0.166667</output>

<result>1/6 = around 0.166667</result>