If you read 30% of a book, what percentage of it is left unread?
一本书看了它的30%，还剩它的百分之几没看？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10)</gadget>
<output>7/10 = around 0.7</output>

<result>7/10 = around 0.7</result>