Tính nhanh a)5238-476+3476 b)125+125+125+125-25-25-25-25 c)175x99+175 d)6x873x3+18x127+9x100x2 e)2008+867+2009x133

`a) 5238 - 476 + 3476`

`= 5238 + ( 3476 - 476 )`

`= 5238 + 3000`

`= 8238`

`b) 125 + 125 + 125 + 125 - 25 - 25 - 25 - 25`

`= ( 125 - 25 ) + ( 122 - 25 ) + ( 125 - 25 ) + ( 125 - 25 )`

`= 100 + 100 + 100 + 100`

`= 400`

`c) 175 xx 99 + 175`

`= 175 xx 99 + 175 xx 1`

`= 175 xx ( 99 + 1 )`

`= 175 xx 100`

`= 17500`

`d) 6 xx 873 xx 3 + 18 xx 127 + 9 xx 100 xx 2`

`= ( 6xx3 ) xx 873 + 18 xx 127 + ( 9 xx 2 ) xx 100`

`= 18 xx 873 + 18 xx 127 + 18 xx 100`

`= 18 xx ( 873 + 127 + 100 )`

`= 18 xx1100`

`= 19800`

`e) 2008 xx 867 + 2009 xx 133`

`= 2008 xx 867 + ( 2008 + 1 ) xx 133`

`= 2008 xx 867 + 2008 xx 133 + 1 xx 133`

`= 2008 xx ( 867 + 133 ) + 133`

`= 2008 xx 1000 + 133`

`= 2008000 + 133`

`= 2008133`