2001+2002+2003+2004+2005+2006+2007-2008=how many.
2001+2002+2003+2004+2005+2006+2007-2008=多少．
<gadget id="calculator">2_007 - 2_008</gadget>
<output>-1</output>

<gadget id="calculator">2_001 + 2_002 + 2_003 + 2_004 + 2_005 + 2_006 + (-1)</gadget>
<output>12_020</output>

<result>12_020</result>