`M=2-5/3+7/6-9/10+11/15-13/21+15/28-17/36+19/45`

`M = 2 - 2/2 . ( 5/3-7/6+9/10-11/15+13/21-15/28+17/36-19/45 )`

`M = 2 - 2 . ( 5/6 - 7/12 + 9/20 - 11/30 + 13/42 - 15/56 + 17/72 - 19/90 )`

`M = 2 - 2 . ( 1/2 + 1/3 - 1/3 - 1/4 + 1/4 + 1/5 - 1/5 - 1/6 + 1/6 - 1/7 + 1/7 + 1/8 - 1/8 - 1/9 + 1/9 - 1/10 )`

`M = 2 - 2 . ( 1/2 - 1/10 )`

`M = 2 - 2 . ( 5/10 - 1/10 )`

`M = 2 - 2 . 2/5`

`M = 2 - 4/5`

`M = 10/5 - 4/5`

`M = 6/5`