Tính bằng cách thuận tiện

2016/2017×13/11-2/11×2016/2017

2/5+3/7+3/5+4/7

2/3×4/8+2/3×5/9

`2016/2017 xx 13/11 - 2/11 xx 2016/2017`

`=2016/2017 xx (13/11 - 2/11)`

`=2016/2017 xx 1`

`=2016/2017`

`2/5 + 3/7 + 3/5 + 4/7`

`=(2/5 + 3/5) + (3/7 + 4/7)`

`=1 + 1`

`=2`

`2/3 xx 4/8 + 2/3 xx 5/9`

`=2/3 xx (4/8 + 5/9)`

`=2/3 xx (36/72 + 40/72)`

`=2/3 xx 76/72`

`=2/3 xx 19/18`

`=19/27`