1+1+2分之1+1+2+3分之1+···+1+2+3+···+18分之1
=1+2/﹙2×3﹚+2/﹙3×4﹚+2/﹙4×5﹚+…+2/﹙18×19﹚
=1+2×﹙1/2-1/3+1/3-1/4+…+1/18-1/19﹚
=1+2×﹙1/2-1/19﹚
=1+1-2/19
=36/19
1+1+2分之1+1+2+3分之1+···+1+2+3+···+18分之1
=1+2/﹙2×3﹚+2/﹙3×4﹚+2/﹙4×5﹚+…+2/﹙18×19﹚
=1+2×﹙1/2-1/3+1/3-1/4+…+1/18-1/19﹚
=1+2×﹙1/2-1/19﹚
=1+1-2/19
=36/19