问题
解答题
1-2+3-4+5-6+…+1991-1992+1993-1994+1995=______.
答案
1-2+3-4+5-6+…+1991-1992+1993-1994+1995,
=(1-2)+(3-4)+(5-6)+…+(1991-1992)+(1993-1994),
=1995-1-1-…-1-1-1,
=998.
1-2+3-4+5-6+…+1991-1992+1993-1994+1995=______.
1-2+3-4+5-6+…+1991-1992+1993-1994+1995,
=(1-2)+(3-4)+(5-6)+…+(1991-1992)+(1993-1994),
=1995-1-1-…-1-1-1,
=998.