2008-1+2-3+4-5+6...1002-1003+1004=how much.
2008-1+2-3+4-5+6…1002-1003+1004=多少．
<gadget id="calculator">1_004 / 2</gadget>
<output>502</output>

<gadget id="calculator">2_008 + 502</gadget>
<output>2_510</output>

<result>2_510</result>