Page 1:

1)( 1) due east, 45 degrees east of south (or southeast), 2, due east, 3.

(2) 50 degrees south by west (or 40 degrees south by west), due west, 3, 45 degrees south by west (or southwest), 2

(3)* Hospital

(4) From the bookstore, take 1 stop to the east of the park, then take 2 stops to the 45-degree library in the southeast, and finally take 2 stops to the east of the hospital.

2)( 1)(60-24+30)÷6 (2)60-(24+30)÷6 (3)60-(24+30÷6)

=(36+30)÷6 =60-54÷6 =60-(24+5)

= 66÷6 =60-9 =60-29

= 1 1 =5 1 =3 1

Page 2:

3)204÷3=68 (tree) ... pear tree

68×2= 136 (tree) ... peach tree

68+ 136+204

=68+( 136+204)

=68+340

=408 (Tree) … Three kinds of fruit trees

A: There are 136 peach trees and 408 three kinds of fruit trees in the orchard.

4) 1 16=20×( 1)+8×( 12)= =20×(3)+8×(7)=20×(5)+8×(2)

A: There are three ways to buy: ① 1 book Selected Fairy Tales and 12 book Tales of Scientists; (2) 3 selected fairy tales and 7 stories of scientists; (3) five selected fairy tales and stories of two scientists.

Expand and explore:

△ =93,▲=26,□=43,■= 14,☆=57,★=38。

Page 3:

1)8 1,28, 124,6,90,27, 198,48,4 1

2)450-225÷5+ 135 25×7 1×4 99×425

=450-45+ 135 =25×4×7 1 =( 100- 1)×425

=450+90 = 100×7 1 = 100×425- 1×425

=540 =7 100 =42500-425

=42075

10 1×79-79 304+306÷ 17-298

=( 10 1- 1)×79 =304+ 18-298

= 100×79 =322-298

= 7900 =24

3)1.56m.

Page 4:

4) 6×4=24 (decimeter) ... Square perimeter (length of iron wire, also rectangular perimeter)

24÷2-8= 12-8=4 (decimeter) ... Rectangular width

8×4=32 (square decimeter) ... Rectangular.

A: Its width is 4 decimeters and its area is 32 square decimeters.

5)3 1× 18=558 (person) 558-24=534 (person) 534=(274)+(260)

Answer: It should be students in Grade One and Grade Two who watch *.

Expand and explore

8+4+2×6=24 8×6÷(4-2)=24 8×4-6-2=24

6×2×(8÷4)=24 (8÷4+2)×6=24

Page 5:

1)4.8 , 3.8 ,3.4 ,2.8 , 1.6

2) Score

Decimal 1.0 0.8 1.8

3)0.2 2.4 0.35 0.9 1. 15 1.2

Page 6:

4)4 tons 500 kg = 4,500 kg

4500÷(60×25)

=4500÷ 1500

=3 kg

A: Each bottle of salad oil weighs 3 kilograms.

5)(66+7 1+63+72+76+69+64+74+68+77)÷ 10

=700÷ 10

=70 years old

A: Their average age is 70.

(8- 1)×4=7×4=28 (person) 8-2=6 (person)

(6- 1)×4=20 (person) 28+20=48 (person)

A: There are 28 people on the first floor and 48 people on the second floor.

Page 8:

1) 102×98 and 100×98+2×98, 99× 102 and 102× 98+002, the other two companies.

2)( 1) , ,0. 1,0.0 1,0.00 1

(2) One thousandth, 0.00 1

(3) ,0.03

(4)5,76,854

(5)8.43, 8.43

(6) Ten o'clock, 0. 1 000, 0.00 1

3)480÷(74-34) 126×5-780÷6

=480÷40 =630- 130

= 12 =500

Page 9:

4)6480÷80=8 1 (days) 6480÷(80+ 10)=6480÷90=72 (days) 8 1-72=9 (days)

A: It actually took nine days less than originally planned.

5) 120÷4=30 (piece) 105÷3=35 (piece) 30 < 35 35-30=5 (piece)

A: Xiaohua's copying speed is very fast, with five more words per minute.

Expand and explore:

Page 10:

1) 128，+，C，B，+，64， 125-25，C，A，B，×，50， 100，2

2)( 1)② (2)② (3)② (4)③ (5)③

extreme

Page 1 1:

3)24×( 145+55)

=24×200

=4800 (yuan)

24×( 145-55)

=24×90

=2 160 (yuan)

A: It cost 4,800 yuan to buy these office desks and chairs, and it cost 2 160 yuan more to buy tables than chairs.

4)(600-375)÷25

=225÷25

=9 (box)

There are 9 boxes more apples than pears.

Expand and explore:

He is 1.46 meters tall and weighs 30.5 kilograms. He drank 0.06 kg of milk in the morning and bought a ballpoint pen for 3.25 yuan at noon.

Page 12:

1)( 1)④ (2)② (3)③ (4)④

2) 20.36 0. 15 0.09 9.509

3) 0.4 0.8 1.8 2.7 3.4 4. 1 4.5

Page 13:

4)(A+B)×(E-F)=G

5)(25-5)×300÷25 or 300-300×5÷25

=20×300÷25 =300- 1500÷25

=6000÷25 =300-60

=240 units =240 units

A: It was originally planned to produce 240 washing machines every day.

Expand and explore:

(! )9+99+999+9999+99999+999999

= 10+ 100+ 1000+ 10000+ 100000+ 1000000

= 1 1 1 1 1 10-6

= 1 1 1 1 104

(2) 1+3+5+7+9+ 1 1+ 13+ 15+ 17+ 19

= (1+19) ×10 ÷ 2 or = (1+19) ÷ 2× (1+19)

=20× 10÷2 = 10× 10

=200÷2 = 100

= 100

Page 15:

1) 160.5 company 165 16.05 company 16.05 1.605 company 1.605 company.

0.605 even 0.605 60.5 even 60.5.

2)×,×,√, ×,×,√

3) This question is not good. There are too many qualified data to compare. Write down six at random and compare the sizes.

4)=，& gt，& gt，& gt，& lt,=

Page 16:

5)8×25+8×(25-5)

=200+ 160

=360 kg

360 kilograms of pears and apples have arrived.

6)20×23+ 18

=460+ 18

=478 km

The artificial earth satellite flies 478 kilometers per hour.

Expand and explore:

1)2508-25.08=2482.92 (yuan)

A: You will find that this book is undercharged by 2482.92 yuan.

2) Because the decimal point is wrong by one place, the book is 95.4 yuan more, that is to say, the original number is expanded by 10 times, which leads to errors, and the book is 9 times more than the original number, so the original number is 95.4( 10- 1).

=95.4÷9

= 10.6 (yuan)

A: He mistyped 10.6 yuan as 106 yuan.

3) Because, if you look at more digits: 8-3=5, and look at ten digits less than 90-60=30, the correct answer should be:

123.8+30-5

= 153.8-5

= 148.8 (yuan)

A: The correct answer to this account number is 148.8 yuan.

Page 17:

1)0.4 15 5.2 180 0. 1 0.06 30 10 0.00503 10 42

2)3 ,4 20 ,2 1 48 ,47 1 ,0 9 , 10 17 , 16

3)×,×,×,×,√

4) Answer: The decimal number is: 630.05, and the correct pronunciation is: 630.05.

Page 18:

5) 1 16+68+(68+ 16)

= 184+84

=268 pages

This story book has 268 pages.

6) 17×5×2

=85×2

= 170 (tree)

A: A * * * can plant 170 seedlings.

Expand and explore:

1)∠2= 180 -∠ 1= 180 - 135 =45

∠3=90 -∠2=90 -45 =45

∠4= 180 -∠5-∠3= 180 -40 -45 =95

2) 180 ,360 ,540 ,720 ,900 …

The sum of the interior angles of a polygon = (number of sides -2) × 180 (n ≥ 3)

Page 19:

1)>，& lt，& lt，& lt，=，=，& gt，& gt,=

2)8 pieces of 0.8, 43 squares of 0.43, 6 squares of 2 cm and 2.6 cm.

3)

4)( 1) right angle (2)60(3) less than (4) isosceles right angle, 45

Page 20:

5)5 ×(4- 1) 8÷4=2 (m)

=5×3

= 15 (minutes)

Answer: It takes 15 minutes to finish sawing, and each section is 2 meters long.

6) 180÷6=30 (line)

(30- 1)× 120

=29× 120

=3480 cm

=34.8 meters

A: This guard of honor has 30 rows, which is 34.8 meters from beginning to end.

Expand and explore:

5 jiao =0.5 yuan.

5×( 1+0.5)

=5× 1.5

=7.5 (yuan)

Answer; At least it will cost 7.5 yuan money.

Tisso

Page 22:

1)5,7,8,5.2,260,7.85,6,40,3.55, 1,80,4.89,4,2,8,8.05

2)& lt； ，=，& lt，& gt，=，& lt

3) = 466.85 million ≈ 467 million = 769.0804 million ≈ 769 million = 20.608 billion = 20.608 billion.

= 97.08 million ≈ 97 million = 320.6 million ≈3.2 1 billion = 70.4009 billion ≈ 70.405438+billion.

4) 1 .67km >:1.4km >120km > 400m

Page 23:

5) 1 ton =1000kg

1000÷ 10×3.6

= 100×3.6

=360 kg

Answer: You can squeeze 360 Jin of peanut oil.

6) 1 hour 40 minutes = 100 minutes

0.25×100 = 25km

A: This bike is 1 hour, 40 minutes and 25 kilometers.

7)(24+20)×5 (24-20)×5

=44×5 =4×5

=220 sheets =20 sheets

Answer: One * * * has 220 small desks, and Class One has moved 20 more than Class Two.

Expand and explore:

∠ 1=∠2=∠3=∠4=60 ÷2=30

∠5= 180 -30 ×2= 180 -60 = 120

Page 24:

1) 92，25，4，b，c，a，c 28 1， 128，72，34， 100，34，2，76，67，33

2) Left 1 connects right 3, left 2 connects right 1, left 3 connects right 4, and left 4 connects right 2.

3)+ , 5 , 5 , 8 , × , 125 , 2 , ×

4)

Page 25:

5) (1)17.5+15.2 = 32.7 (yuan)

32.7 >30.8

32.7-30.8= 1.9 (yuan)

A: Congcong spends a lot of money. 1.9 yuan.

(2)30.8 >27.4 >24.7 > 19.4 > 17.5 > 15.2

Choose the cheapest three:19.4+17.5+15.2.

=36.9+ 15.2

=52. 1 (yuan)

52. 1 >50

Not enough money.

Expand and explore:

1) longest: (12) < 5+8 shortest: (4)>8-5.

A: The third side can be any integer between 4 and 12.

2)90 ÷(2+ 1)

=90 ÷3

=30 30 ×2=60

A: The two acute angles are 30 and 60 respectively.

3) A. Assuming that 60 is the top angle, the bottom angle is (180-60) ÷ 2 =120 ÷ 2 = 60.

B suppose 60 is the base angle and the top angle is180-60× 2 = 60.

A: The other two angles are 60, which are equilateral triangles.

Page 26:

1)7.2 1.8 3.5 2.8 4.5 0.8 20 14.3 1.35

40 3.02 0.92 2.7 0.7 7

2)AB CB DB

3)4

4)∠2=∠4= 180 -30 = 150 ∠3=∠ 1=30

Answer: ∠ 2 = 150, ∠ 3 = 30, ∠ 4 = 150.

Page 27:

5)( 1)(40+50+ 1 10+80)÷4

=280÷4

=70 (yuan)

A: The average electricity bill of Mr. Wang's family in these four months is 70 yuan.

(2) A: I estimate that the month of C is 1, because it was very cold at that time and people used a lot of electricity for heating.

(3) Answer: I predict that the electricity bill for next month may be around 50 yuan, because the spring blossoms in March, the temperature is suitable, and there is not much electricity for heating.

Expand and explore:

150÷ 15×2-2

=20-2

= 18 (lamp)

A: A * * * needs to install 18 lamps.

Page 29:

1)52.5 49.6 8 1.2

19. 1 14.5 28

2)=0.3+0. 1+0.6 =0.7-0.37+0.03 = 0.56-0.023-0.02 =0.095+0.7-0.07

=0.4+0.6 =0.33+0.03 =0.537-0.02 =0.795-0.07

= 1 =0.36 =0.5 17 =0.725

3)=4.25 yuan +8.07 yuan =6.045 km +7.3 km

= 12.32 yuan = 13.345km.

=52 tons +8.0002 tons = 50.08m-40.5m.

=60.0002 tons =9.58 meters

4) Answer: It may be an acute triangle, a right triangle or an obtuse triangle.

Page 30:

5)5- 1=4 (pieces) 13- 1= 12 (pieces) 12÷4×2=3×2=6 (points)

A: A * * * takes 6 minutes.

6)90×3-(76+ 1 14)

=270- 190

=80 (yuan)

A: 80 yuan plans to use electricity in the last month.

Expand and explore:

Analysis: A's age is equal to B's age plus 6. C is twice as old as A, that is, twice as old as B plus 6, so twice as old as B plus 2 6 is B's 22 years old.

B: 22-2×6= 10 (year) A: 10+6= 16 (year) C: 10+22=32 (year).

Total age of three people: 10+ 16+32=58 (years).

A: The total age of the three of them is 58.

;