=(2010+2009)(2010-2209)+(2008+2007)(2008-2007)+(2006+2005)(2006-2005)+……+(2+1)(2-1)
=2010+2009+2008+2007+……+1
=(2010+1)*1005
=2021055
=(2010+2009)(2010-2209)+(2008+2007)(2008-2007)+(2006+2005)(2006-2005)+……+(2+1)(2-1)
=2010+2009+2008+2007+……+1
=(2010+1)*1005
=2021055