2008*2006+2007*2005-2007*2006-2008*2005=how much.
2008*2006+2007*2005-2007*2006-2008*2005=多少．
<gadget id="calculator">2_008 * 2_006</gadget>
<output>4_028_048</output>

<gadget id="calculator">2_007 * 2_005</gadget>
<output>4_024_035</output>

<gadget id="calculator">2_007 * 2_006</gadget>
<output>4_026_042</output>

<gadget id="calculator">2_008 * 2_005</gadget>
<output>4_026_040</output>

<gadget id="calculator">4_024_035 - 4_026_042 - 4_026_040</gadget>
<output>-4_028_047</output>

<gadget id="calculator">4_028_048 + (-4_028_047)</gadget>
<output>1</output>

<result>1</result>