The London Olympic Organizing Committee announced that the 30th Summer Olympic Games in 2012 will open on July 27, 2012 local time, and close on August 12, 2012. How many days did the Olympic Games last? How many
伦敦奥组委宣布2012年第30届夏季奥运会将于当地时间2012年7月27日开幕，闭幕时间为2012年8月12日．本届奥运会开了多少天？多少
<gadget id="calculator">31 - 27</gadget>
<output>4</output>

<gadget id="calculator">4 + 1 + 12</gadget>
<output>17</output>

<result>17</result>