I. 31.2,8.7, 1.26,12,4

17,0.4, 0.24, 3 , 0.06, 15

Two. 4. 14, 0. 144, 2.04, 28

Three. 16.25, 162.5, 0. 1625,42, 0.42, 0.42.

Four. 15.6, 27.72

Page two:

Four. 2.25, 4. 16, 25.75, 82

Verb (abbreviation of verb) 4.8×3.2÷2 2.8× 1.6

= 15.36÷2 =4.48 (square centimeter)

=7.68 (square centimeter)

(2.4+4.6)×3.2÷2(8.4+ 1 1.8)×7.5÷2

=7×3.2÷2=20.2×7.5÷2

= 1 1.2 (square centimeter) =75.75 (square centimeter)

Page three:

Sixth, solve the problem.

1, 680 ÷ 4× 3.2 =170× 3.2 = 544km.

2. ① 541.8÷15 = 36.12 (m)

② 54 1.8÷7= 77.4 (m)

③ 77.4-36.12 = 41.28 (m)

3. 185×5.4= 999 km

4.0.8× 24×18 =19.2×18 = 345.6 (yuan)

Page four:

5.324×1.2+48 = 388.8+48 = 436.8 (yuan)

Improved articles:

1、28

2、 392.6× 192-39260×0.927.5×23+3 1×2.5

=392.6× 192-392.6×92=2.5×(3×23)+3 1×2.5

=392.6×( 192-92)=2.5×(69+3 1)

=392.6× 100 =2.5× 100

=39260=250

3、 0.79×0.46+7.9×0.24+ 1 1.4×0.079

=0.79×0.46+0.79×2.4+ 1. 14×0.79

=0.79×(0.46+2.4+ 1. 14)

=0.79×4

=3. 16

Page five:

1 、>; ，& lt，& lt，& lt，& gt，& gt

2、32.37.7

3、0.832.46

4、0.56× 10 1 =0.56× 100+0.56× 1=56+0.56=56.56

2.37×0.5×4=2.37×(0.5×4)=2.37×2=4.74

3.7×2.5+6.3×2.5=(3.7+6.3)×2.5= 10×2.5=25

1.2×0.25=4×0.25×0.3= 1×0.3=0.3

0.25×6.9×0.4=0.25×0.4×6.9=0. 1×6.9=0.69

0.25×32× 1.25=0.25×4×(8× 1.25)= 1× 10= 10

Page six:

5. Perimeter (4.8+3.2)×2=8×2= 16 (cm)

Area 4.8×3= 14.4 (square centimeter)

6, 1) 4.75× 1.2=5.7 (yuan)

2) Length 6×1.5 = 9m× 6 = 54m 2.

Or 6× 1.5×6=9×6=54 (square meter)

3) (35.7+24.3) × 25 = 60× 25 =1500 (yuan)

Page seven:

4)15× 0.45 = 6.75km 6× 0.9 = 5.4km.

6.75 & gt5.4

A: Teacher Li's home is 6.75 kilometers away from school, so it takes 0.9 hours to get to school.

5) 2.94× 23 = 67.62m ≈ 68m

6) 6.5× 4 ÷ 2 ÷100×12 = 0.13×12 =14.

Page 8:

7)24× 18.5=444 (square centimeter)

8)4.8× 1.5÷2=7.2÷2=3.6 (square centimeter)

(2.7+6.3)×5÷2=45÷2=22.5 (square decimeter)

9)10× 20+(12-10 )× (20-14) ÷ 2 = 200+6 = 206 (square centimeter) (various methods).

Improved articles:

1, the decimal point of a number is shifted one place to the right, indicating that b number is 10 times of a number.

Solution: Let the number A be x, then the number B is 10X.

10X-X=7.02

X = 0.78， 10x = 7.8。

Or first find the number of armour 7.02÷( 10- 1)=0.78.

Find the second number 7.02+0.78=7.8.

2、 10.5×5+ 1 1.3×4-9.3×8

=52.5+45.2-74.4

=23.3

3. How many people per person: 9÷3=3 (1)

A spends more money on bread: 5-3=2 (pieces)

How much is a loaf of bread: 1.2÷3=0.4 yuan.

Amount recovered by Party A: 0.4×2=0.8 (Yuan)

Page 9:

1、8,6 ,6

0.8,6,0.6

0.8,6,0.6

80,0.6,6

2、0.4545450

3, all wrong, the first question should be 0.07, and the second question should be 2.5.

4、 19, 6.7, 1.28,9 , 570, 1.6,

Page 10:

35, 1 1

5、90 ,50.8, 15,0.8

6. Unit price of milk: 1.65 Unit price of beef: 1 1.50 Fish quantity: 1.6.

Total cake 15.80, total receivable 55.00, change 45.00.

Page 1 1:

1, 67.2÷4= 16.8 (yuan)

2,410.5 ÷ 5 = 82.1(km/h)

3,45.6 ÷ 7.6 = 6 (ton)

4,3.7 ÷ 0.4 ≈10 (pieces)

Page 12:

5430.6÷24≈ 17 (set)

430.6-24×15 = 430.6-360 = 70.6 (yuan)

70.6÷2 1≈3 (set)

Improved articles:

1、 0.9999×0.7+0. 1 1 1 1×2.7=0.9999×0.7+0.9999×0.3

=0.9999×(0.7+0.3)=0.9999× 1=0.9999

(3.4×4.8×9.5)÷( 1.9× 1.7×2.4)=(3.4÷ 1.7)×(4.8

÷2.4)×(9.5÷ 1.9)=2×2×5=20

2、 0.47÷9.4=0.05 1.54-0.3 1= 1.23 1.23+0.05= 1.28

Fill in 1.28 in the box.

4、4.9+(4.9+9.8)+(4.9+9.8×2)+ …+(4.9+9.8×9)

=4.9× 10+9.8×( 1+2+…+9)

=49+44 1

=490 meters

Page 13:

1, limited decimal: 5.0 10 1, 3.4567, 5.0411,8.9, 9.7643, 3.99.

. . ..。

Cyclic decimal: 4. 1.6, 8.7, 8.69, 0.9323..., 2.9595. ...

Infinite cycle decimal number: 3.45789 ...

2、 0. 168 125,0. 18,

3. Looking horizontally: Check questions 2, 3, 4 and 5.

Page 14:

4 、( 1.5+ 18.5)+A(2.3+7.7)×X(A×C)×B

5、0. 143,2.333,0.0 18, 10.325,8.244

6. How high is the refrigerator? 0.85× 1.8= 1.53 (m)

How much taller is the refrigerator than the child?

1.53—0.85=0.68 (m) or 0.85× (1.8—1) = 0.68 (m).

...。 . ..

7、0. 1 99 6 >0. 1 9 9 6 >0. 1996 >0. 1 996

Page 15:

8,1) 405 ÷ 5 ÷ 2.7 = 81÷ 2.7 = 30 (m)

2) 249.6-249.6 ÷ 2.4 = 249.6-104 =145.6 (m)

Or 249.6 ÷ 2.4× (2.4-1) =104×1.4 =145.6 (m).

3) (1.26+1.74) ×15 = 3×15 = 45 (m)

Improved articles:

1、 1) 199. 199× 198- 198. 198× 199

= 199. 199×( 199- 1) -( 199. 199- 1.00 1)× 199

= 199. 199× 199- 199. 199- 199. 199× 199+ 199. 199

=0

Page 16:

2) 18.9× 178. 178+0.49- 17.8× 189. 189

= 18.9× 178× 1.00 1+0.49- 17.8× 189× 1.00 1

=0.49

2、 1)2n

2)a+(a+6)+(a+6×2)+…+(a+6×5)= 6a+6×( 1+2+…+5)= 6a+90

3) Five triangular numbers from big to small,

The area of 1 is: 32×32÷2=5 12 (square centimeter).

The area of No.2 is: 5 12÷2=256 (square centimeter).

The area of No.3 is: 256÷2= 128 (square centimeter).

The area of No.4 is: 128÷2=64 (square centimeter).

The area of No.5 is: 64÷2=32 (square centimeter).

512+256+128+64+32 = 992 (square centimeter)

Page 17:

1、9.3, 9.34,9.343

0.2 ,0. 16,0. 159

5.7 ,5.67,5.667

4.3,4.32,4.3 17

2,3 The second question is not 0.9 1.4.

3. Lines 1, 1, 2, 1, 2, 4.

Line 1, line 3, line 2, line 1, line 4, line 2, line 3

Page 18:

4、ax，bx，ax+bx

5, 1)93.6÷9= 10.4 (m)

2) 380,000 yuan = 380,000 yuan

380000÷ 158.09≈2403.69 (yuan)

3) 392÷9.5≈4 1 (km/h)

Page 19:

4) 95.2÷( 163.2÷2.4)=95.2÷68= 1.4

5) We love science. 8=25 (Ben)

Comic world 353.7÷ 13. 1=27 (Ben)

One Thousand and One Nights 381.6÷ 21.2 =18 (Ben)

27 >； 25 >； 18

A: comic world is the best seller.