|1/11-1/11|+|1/11-1/12|+|1/13-1/12|
=1/11-1/11+1/11-1/12+1/12-1/13
=1/11-1/13
=2/143
|1/3-1/2|+|1/4-1/3|+|1/5-1/4|+……+|1/10-1/9|
=1/2-1/3-1/3+1/4-1/4+1/5+……1/9-1/9+1/10
=1/2+1/10
=6/10
=3/5
|1/11-1/11|+|1/11-1/12|+|1/13-1/12|
=1/11-1/11+1/11-1/12+1/12-1/13
=1/11-1/13
=2/143
|1/3-1/2|+|1/4-1/3|+|1/5-1/4|+……+|1/10-1/9|
=1/2-1/3-1/3+1/4-1/4+1/5+……1/9-1/9+1/10
=1/2+1/10
=6/10
=3/5