1 : Tính nhanh:

a) 2376 + 3425 - 376 - 425 = ( 2376 - 376 ) + ( 3425 - 425 )

                                       = 2000 + 3000

                                       = 5000

b)4638 - 2437 + 5362 - 7563 = 2210 + ( - 2210 )

                                          = 0

c) 45 + 45 + 45 + 45 + 15 + 15 + 15 + 15

  = 45 x 4 + 15 x 4

 = ( 45 + 15 ) x 4

 = 60 x 4

 = 240

d) 4 x 125 x 25 x 8 = ( 4 x 25 ) x ( 125 x 8 )

                            = 100 x 1000

                            = 100000

e) 2 x 8 x 50 x 25 x 125 = ( 2 x 50 ) x ( 8 x 125 ) x 25

                                   = 100 x 1000 x 25

                                   = 100000 x 25

                                   = 2500000

2 : Tính nhanh bằng 2 cách:

C1 : 125 + 125 + 125 + 125 - 25 - 25 - 25 - 25

    = ( 125 - 25 ) + ( 125 - 25) + ( 125 - 25 ) + ( 125 - 25 )

    =100 + 100 + 100 + 100 

    = 100 x 4 

    = 400

C2 : 125 + 125 + 125 + 125 - 25 - 25 - 25 - 25

     = 125 x 4 - 25 x 4

     = ( 125 - 25 ) x 4

     = 100 x 4

     = 400

1.

a. 5000
b. 0

c. 240

d. 100000

e. 2500000

2.

400

1: Tính nhanh:

a, 2376 + 3425 - 376 - 425

 = ( 2376 - 376 ) + ( 3425 - 425 )

 = 2000 + 3000

 = 5000.

b, 4638 - 2437 + 5362 - 7563

 = 2210 + (-2210)

 = 0.

c, 45 + 45 + 45 + 45 + 15 + 15 + 15 + 15 + 15

 = ( 45 + 15 ) +  ( 45 + 15 ) +  ( 45 + 15 ) +  ( 45 + 15 ) 

 = 60 + 60 + 60 + 60

 = 240.

d, 4 x 125 x 25 x 8 

 = ( 4 x 25 ) x ( 125 x 8 )

 = 100 x 1000

 = 100000.

e, 2 x 8 x 50 x 25 x 125

 = ( 2 x 50 ) x ( 8 x 125 ) x 25

 = 100 x 1000 x 25

 = 2500000.

2: Tính nhanh bằng hai cách:

  125 + 125 + 125 + 125 - 25 - 25 - 25- 25

= ( 125 - 25 ) + ( 125 - 25 ) + ( 125 - 25 ) + ( 125 -25 )

= 100 + 100 + 100 + 100

= 400.

(2x50)+(4x25)+(125x8) x3 = 3300

4 × 125 × 25 × 8

= (4 × 25) × (125 × 8)

= 100 × 1000

= 100 000

2 × 8 × 50 × 25 × 125

= (2 × 50) × (8 × 125) × 25

= 100 × 1000 × 125

= 12 500 000

2 × 3 × 4 × 5 × 50 × 25

= (2 × 50) × (4 × 25) × (3 × 5)

= 100 × 100 × 15

= 150 000

25 × 20 × 125 × 8 - 8 × 20 × 5 × 125

= 8 × 125 × 20 × (25 - 5)

= 1000 × 20 × 20

= 400 000

- (25 x 4) x (125 x8)=100 x 1000 =100000

- (50 x 2) x (8 x 125) x 25=100 x 1000 x 25 =2500000

- (2 x 50 ) x (4 x 25) x (3 x5)=100 x 100 x 15=150000

- 25 x 20 x125 x 8 - 5

= (20 x 5) x (125 x 8) -25=100 x 1000 -5 =100000 - 5 =99995

4 *125*25*8

=4*25*125*8

=100*1000

=100000

2*8*50*25*125

=2*50*8*125*25

=100*1000*25

=2500000

2*3*4*5*50*25

=2*50*4*25*3*5

=100*100*15

=150000

25*20*125*8-8*20*5*125

=25*4*5*125*8-8*125*20*5

=100*1000*5-1000*100

=500000-100000

=400000

=

2 x 3 x 4 x 8 x 50 x 25 x 125

          = 3 x 2 x 4 x 50 x 8 x 25 x 125

          = 3 x (2 x 50) x (4 x 25) x (8 x 125)

          = 30 000 000.

2x3x4x850x25x125=31875000

t đi tôi k lại

\(2x3x4x8x50x25x125=\left(2x50\right)x\left(4x25\right)x\left(8x125\right)x3\)\(=100x100x1000x3=30000000\)

=31875000

t đi tôi t lại

Trl:

\(\left(-4\right)\times\left(+125\right)\times\left(-25\right)\times\left(-6\right)\times\left(-8\right)\)

\(=\left[\left(-4\right)\times\left(-25\right)\right]\times\left[\left(+125\right)\times\left(-8\right)\right]\times\left(-6\right)\)

\(=100\times\left(-1000\right)\times\left(-6\right)\)

\(=\left(-100000\right)\times\left(-6\right)\)

\(=600000\)

2 x 8 x 50 x 25 x 125       

= ( 125 x 8 ) x ( 50 x 2 ) x 25

= 1000 x 100 x 25

=2500000

4 x 125 x 25 x  8 

= ( 125 x 8 ) x ( 25 x 4 )

= 1000 x 100

=100000

2 x 3 x 4 x 5 x 50 x 25    

= ( 25 x 4 ) x ( 2 x 50 ) x ( 3 x 5 )

= 100 x 100 x 15

= 150000

  25 x 20 x 125 x 8 -  8 x 20 x 5 x 125

= ( 25 x 20 ) x ( 125 x 8 ) - ( 20 x 5 ) x ( 125 x 8 )

= 500 x 1000 - 100 x 1000

= 500000 - 100000

= 400000

4 x 125 x 25 x 8

= (4x25) x (125x8)

=100x1000

=100000

4 x 125 x 25 x 8

= ( 4 x 25 ) x ( 125 x 8 )

= 100         x 1000

=     100000

   2 x 8 x 50 x 25 x 125

=  ( 2 x 50 ) x ( 8 x 125 ) x 25

=    100       x 1000        x 25

=     100000                  x 25

=              2500000

    2 x 3 x 4 x 5 x 50 x 25

=  ( 2 x 50 ) x ( 4 x 25 ) x 3 x 5

=   100        x    100     x 3 x 5 

=        10000               x 15

=       150000

  25 x 20 x 125 x 8 - 8 x 20 x 5 x 125

= ( 8 x 125 ) x 25 x 20 - ( 8 x 125 ) x ( 20 x 5 )

=  1000        x 50        - 1000         x 100

=       50000                - 100000

=           - 50000

Chúc bạn hok tốt !

Lời giải:
1. Bạn coi lại đề

2. $=234\times (1257-257)=234\times 1000=234000$

3. $=175\times (1274-273-1)=175\times 1000=175000$

4. $=(4\times 25)\times (125\times 8)=100\times 1000=100000$

1. ...............................

2. $=234\times (1257-257)=234\times 1000=234000$

3. $=175\times (1274-273-1)=175\times 1000=175000$

4. $=(4\times 25)\times (125\times 8)=100\times 1000=100000$

4 x 20 x 25 x 5 x 125 x 10 x 10 x 8 = ( 25 x 4 ) x ( 20 x 5 ) x ( 125 x 8 ) x ( 10 x 10 )

                                                        = 100 x 100 x 1000 x 100

                                                        = 1 000 000 000

4x20x25x5x125x10x10x8

=(4x25)x(125x8)x(10x10)x(20x5)

=100x1000x100x100

=1000000000

 4 × 20 × 25 × 5 × 125 × 10 × 10 × 8 

= ( 4 × 25 ) × ( 20 × 5 ) × ( 10 × 10 ) × ( 125 × 8 ) 

= 100 × 100 × 100 × 1000

= 10 000 × 100 × 1000

= 1 000 000 × 1000

= 1 000 000 000