Các sư phụ giúp e với

`2)` Tính hợp lí: 

 `a) 882 +139 +18+61`

`= (882+18)+(139+61)`

`=900+200`

`=1100`

`b)` `2783+125+7217+575`

`=(2783+7217)+(125+575)`

`=10000+700=10700`

`c)` `5xx4xx35xx25xx20`

`= (5xx20)xx(4xx25)xx35`

`= 100xx100xx35`

`= 350000`

`d) 8×2×2023×125×5`

`=(8×125)xx (2xx5)xx 2023`

`= 1000×10×2023`

`= 20230000`

`e) 2^3xx28-2^3xx25`

`= 2^3xx(28-25)`

`=8xx3`

`=24`

`g) 15xx19+80xx15+15`

`=15xx(80+19+1)`

`=15xx100`

`= 1500`

`h) 17xx85+15xx17-350`

`= 17xx( 85+15)-350`

`=17xx100-350`

`= 1700−350`

`=1350`

`i) 31xx175-31xx50+69xx125`

`=31xx(175−50)+69×125`

`= 31×125+69×125`

`= (31+69)×125`

`= 100xx125`

`= 12500`