Simple calculation: 2004+2003-2002-2001+1999-1998-1997+...+8+7-6-5+4+3-2-1.
简便运算：2004+2003-2002-2001+1999-1998-1997+…+8+7-6-5+4+3-2-1．
<gadget id="calculator">2 * 1_002</gadget>
<output>2_004</output>

<result>2_004</result>