Question

 

Tinh nhanh 

1 } 42 x 91 + 6 x 19 x 7 - 420

2 ) 99 x 1001 - 99

 

Answer 1

A=42 x91+6x19x7-420=42x91+(6x7)x19-42x10=42x(91+19-10)=42x(110-10)=42x100=4200

Answer 2

1:4200

2:99000

Answer 3

 Tinh nhanh 1 } 42 x 91 + 6 x 19 x 7 - 4202 ) 99 x 1001 - 99 

Answer 4

1) 42 x 91 + 6 x 19 x 7 - 420

= 42 x 91 + 6 x 7 x 19 - 42 x 10

= 42 x 91 + 42 x 19 - 42 x 10

= 42 x ( 91 + 19 - 10 )

= 42 x 100

= 4200

2) 99 x 1001 - 99

= 99 x ( 1001 - 1 )

= 99 x 1000

= 99000

Answer 5

1) 42 x 91 + 6 x 19 x7 - 420

= 42 x 91 + 42 x 19 - 420

= 42 x ( 91 + 19) - 420

= 42 x 100 - 420

= 4200 - 420

= 3780

2) 99 x 1001 - 99

= 99 x 1000 + 99 -99

= 99000 + 0

= 99000

Đúng chưa? 

Answer 6

1 : 3780 hoặc 4200 

2 : 99000

 Đúng nha Nguyễn Như Quỳnh

Answer 7

99x1001-99=99x1001-99x1=99x(1001-1)=99x1000=99000