Xiao Ming reads a science fiction book. On the first day, he reads the whole book (2/7), what percentage of the book is left unread?
小明看一本科幻书，第一天看了全书的(2/7)，还剩几分之几没有看？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (2/7)</gadget>
<output>5/7 = around 0.714286</output>

<result>5/7 = around 0.714286</result>