-1+2-3+4-5+6……-2001+2002+-2003+2004
=(-1+2)+(-3+4)+(-5+6)+……+(-2001+2002)+(-2003+2004)
=1+1+1+……+1+1 [共有1002个1]
=1002
(2-1)+(4-3)+(6-5)............+(2002-2001)+(2004-2003)=1002
-1 2=1,-3 4=1,,,依次类推得共有1002个1所以答案=1002
-1+2+-3+4-5+6……-2001+2002+-2003+2004
=1X(2004÷2)
=1002
-1+2+-3+4-5+6……-2001+2002+-2003+2004
=1*2004/2
=1*1002
=1002