Hỏi đáp bài tập

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

=

Hướng dẫn giải:

a) 3 x (20 – 5)

Cách 1:

3 x (20 – 5) = 3 x 15 = 45

Cách 2:

3 x (20 – 5) = 3 x 20 – 3 x 5 = 60 – 15 = 45

b) 20 x (40 – 1)

Cách 1:

20 x (40 – 1) = 20 x 39 = 780

Cách 2:

20 x (40 – 1) = 20 x 40 – 20 x 1 = 800 – 20 = 780