原式=1+2+1/﹙2×3﹚+3+1/﹙3×4﹚+4+1/﹙4×5﹚+5+1/﹙5×6﹚+6+1/﹙6×7﹚+7+1/﹙7×8﹚+8+1/﹙8×9﹚
=1+2+……+8+1/2-1/3+1/3-1/4+………+1/8-1/9
=36+1/2-1/9
=36又7/18
原式=1+2+1/﹙2×3﹚+3+1/﹙3×4﹚+4+1/﹙4×5﹚+5+1/﹙5×6﹚+6+1/﹙6×7﹚+7+1/﹙7×8﹚+8+1/﹙8×9﹚
=1+2+……+8+1/2-1/3+1/3-1/4+………+1/8-1/9
=36+1/2-1/9
=36又7/18