1-2+3-4+5-6+…-2000+2001=
问题描述:
1-2+3-4+5-6+…-2000+2001=
算算看呢
答
1-2+3-4+5-6+…-2000+2001 =(1-2)+(3-4)+(5-6)+...+(1999-2000)+2001 =-1-1-1-...-1+2001 =-1000+2001 =1001