计算: 1-3+5-7+9-11+…-1999+2001=_.
问题描述:
计算:
1-3+5-7+9-11+…-1999+2001=______.
答
1-3+5-7+9-11+…-1999+2001
=1+(5-3)+(9-7)+(13-11)+…+(2001-1999);
=1+2×500;
=1001.