(2+4+6+...+2006)-(1+3+5+7+...2005)=how much.
(2+4+6+…+2006)-(1+3+5+7+…2005)=多少．
<gadget id="calculator">2_006 - 2_005</gadget>
<output>1</output>

<gadget id="calculator">1 * 1_003</gadget>
<output>1_003</output>

<result>1_003</result>