n(n+1)=[n(n+1)(n+2)-(n-1)n(n+1)]/3
1×2+2×3+…+100×101
=（-0×1×2+1×2×3）/3+（-1×2×3+2×3×4）/3+.+（-99×100×101+100×101×102）/3
=100×101×102/3=343400
1×2+2×3+…+2009×2010
=（-0×1×2+1×2×3）/3+（-1×2×3+2×3×4）/3+.+（-2008×2009×2010+2009×2010×2011）/3
=2009×2010×2011/3
=2706866330