Calculation: 2010*2009-2009*2008-2008*2007+2007*2006.
计算：2010*2009-2009*2008-2008*2007+2007*2006．
<gadget id="calculator">2_010 * 2_009</gadget>
<output>4_038_090</output>

<gadget id="calculator">2_009 * 2_008</gadget>
<output>4_034_072</output>

<gadget id="calculator">2_008 * 2_007</gadget>
<output>4_030_056</output>

<gadget id="calculator">4_038_090 - 4_034_072 - 4_030_056</gadget>
<output>-4_026_038</output>

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

<gadget id="calculator">(-4_026_038) + 4_026_042</gadget>
<output>4</output>

<result>4</result>