(2007-1)+(2006-2)+(2005-3)…(1005-1003)=?

问题描述:

(2007-1)+(2006-2)+(2005-3)…(1005-1003)=?

楼主,
原式= (2007+2006+2005+----+1005)-(1+2+3+-----+1003)
=(2007-1003)+(2006-1002)+-----+(1005-1)
=1004* 1003(组)
=1007012