Đáp án:

a) 8 x 427 x 3 + 6 x 573 x 4 = 24 000
b) 6 x 1235 x 20 - 5 x 235 x 24 = 120 000
c) (145 x 99 +145) - 143 x 101 - 143 = 200
d) 54 x 47 - 47 x 53 - 20 - 27 = 0

 

`a)`

`8 × 427 × 3 + 6 × 573 × 4`

`= 8 × 427 × 3 + 2 × 3 × 573 × 4`

`= 8 × 427 × 3 × 3 × 573 × 8`

`= 8 × 3 × ( 427 + 573 )`

`= 24 × 1000`

`= 24000`

`b)`

`6 × 1235 × 20 - 5 × 235 × 24`

`= 6 × 1235 × 4 × 5 - 5 × 235 × 24`

`= 24 × 1235 × 5 - 5 × 235 × 24`

`= 24 × 5 × ( 1235 - 235 )`

`= 120 × 1000`

`= 120000`

`c)`

`( 145 × 99 + 145 ) - 143 × 101 - 143`

`= ( 145 × 99 + 145 × 1 ) - 143 × 101 - 143 × 1`

`= [ 145 × ( 99 + 1 ) ] - 143 × ( 101 - 1)`

`= [ 145 × 100 ] - 143 × 100`

`= 14500 - 14300`

`= 200`

`d)`

`54 × 47 - 47 × 53 - 20 - 27`

`= 47 × ( 54 - 53 ) - ( 20 + 27 )`

`= 47 × 1 - 47`

`= 47 - 47`

`= 0`

`@``T``i``n``a`