6+7+8-9-10+11+12+13-14-15+……+96+97+98-99-100=?
问题描述:
6+7+8-9-10+11+12+13-14-15+……+96+97+98-99-100=?
答
=6+11+16+...+96-4X20 =1|2X(6+96)X19-80 =969-80=889
6+7+8-9-10+11+12+13-14-15+……+96+97+98-99-100=?
=6+11+16+...+96-4X20 =1|2X(6+96)X19-80 =969-80=889