1 、1/1×2 +1/2×3 +1/3×4 +1/4×5+……1/2010×2011
=1-1/2+1/2-1/3+1/3-1/4+...+1/2010-1/2011
=1-1/2011
=2010/2011
2 、0.2¹º×(-5)¹...