2008×2007-2007×2006+2006×2005-2005×2004+…+2×1
=(2008-2006)*2007+(2006-2004)*2005+…+(4-2)*3+2*1
=2*(2007+2005+2003+…+3)+2
=2*(2007+3)*1003/2+2
=2016032
2008×2007-2007×2006+2006×2005-2005×2004+…+2×1
=(2008-2006)*2007+(2006-2004)*2005+…+(4-2)*3+2*1
=2*(2007+2005+2003+…+3)+2
=2*(2007+3)*1003/2+2
=2016032