Mr. Li downloaded a file, and 70% of it has been downloaded, and how much is left to be downloaded.
李老师下载一份文件，已经下载了70%，还剩多少没下载完．
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>