P2-3
1、30 400 200 40
300 75 100 40
3000 30 3600 150
100 0 60 500
2. Omission
3、6......5; 190; 43.....4; 90......3
4. Omission
5、 1/2; 2/9
Use your head, 48
P4 No.5
1、 120; 120; 400; 350;
120; 120; 4000; 3500;
1200; 1200; 4000; 35000;
12000; 12000; 40000; 325000
2. Omission
3、60*2= 120; 20*6= 120; 30*4= 120; 40*3= 120
4、 135; 2
3500; 39
10
5、2/8+4/8=6/8; 6/6-5/6= 1/6
Use your head
60
P6 No.7
1、800; 1800; 2400; 260
3000; 240; 4200; 480
18000; 2000; 480; 4800
1500; 770; 1600; 7200
2. Hours, minutes and seconds
60; 60
180; 10800; 2; 420; four
3、20; 200; 2000; The divisor is constant, and the dividend is enlarged by 10, 100, 1000, and the quotient is also enlarged by 10, 1000.
360、3600、36000; If one factor remains unchanged, the other factor is enlarged by 10, 100, 1000, and the product is also enlarged by 10, 1000.
4. time; g； g； cm； rice
5、5; 20 or 62, etc
Exercise the brain.
1 1 1 1 1;
six
1234567
123456; seven
P8-9
1、 19; 30; 5 1; 17
28; 62; 19; 1 1;
25; 19; 38; 1 1;
87; 25; 4 1; 47
2、 1422; 856-728= 128
3. Omission
4、60; 180; 1 min 30 seconds; 490
5、0.3; 1.4; 1.9; 2.7; 3.8
6. Omission
7,6 * 6 = 36 (block); 900*36=32400 (square centimeter) 32400 square centimeter =324 square decimeter
Exercise the brain.
2*6+4+8=24; 8/4*2*6=24; ......
3*6+7- 1=24; (7-3)*6* 1=24 ......
P 10- 1 1
1、0.9; 1.6; 1.3; 4.5
1.2; 2 1.5; 8. 1; six
2; 3.6; 1600; 5. 1
8.3; 35.8; 0.4; 3.3
2、3/5; 5/8; 6/6 4/7
3/8 4/4 5/ 10 5/9
3、 40
4.9.30
February 29(th)
The fourth of July.
Use your head:
Area: 8*3*2=48 square centimeters; 3*3=9 square centimeters 48-9=39 square centimeters
Circumference: 8*2+3*2+(8-3)*2=32 cm.
P 12- 13
1, omitted
2, the law: a rectangle with equal perimeter, when the length and width are equal, the area.
3 、& lt； & lt； & lt
& lt； & lt； & lt
=; & lt； =
3、 6....... 1; 3......2
VII ..... 4; correct
4、6; nine
Use your head: 999+999= 1998
p 14- 15
1、 100; 600; 3200; 240
1800; 70; 330; 400;
460; 300; 420; 2 10;
770; 400; 84; 750
2. 1900; 1949 average year; Leap year 2008; 1842 average year; Leap year 2000; Average year in 2006
3.7:55(20 minutes) 8: 15(45 minutes) 9:00.
4, 40/5=8 sets; 8-2=6 sets.
5、5、( 1)3-9; nine
(2)4; six
6. Omission
Use your head: 90
P 16- 17
1、 1400; 840; 650; 1220;
550; 900; 73; celebrity
1 10; 1600; 9....... 1; 67
4/8; 2 10; 28; 340
2、3776; 4778;
2035; 1620
3. Omission
4、2/6; 2/4
5, 50 cm =0.5 meters
1*(0.5+0.5)= 1 m2
Use your head:
50/( 1+3)= 12......2
The person who reports first reports 2. Next, the opponent reports a number, and the person who reports first reports 4-this number; No matter how the opponent reports, as long as the sum of each round is 4, he wins.
P 18- 19
1、2 100; 74; 0.3; Eight hundred
550; 20; VII ... 1; 900
24000; 23; 5600; VII ... 1
340; 1.9; 500; 320
2. Green ball; Yellow ball; Green ball
3、7; 8; 9;
224; 256; 288
4、7.3; 0.8; 650
3/ 10;
9; 3/ 1 1
Exercise the brain.
Squirrel; cat
deer
P20-2 1
1、7......3; 30; 0.6; 960
6400; 66; 5400 ; 200
660; 94; 500; 0.9
300; 100; 90; 2/4
2. Zhang Qiang is the first; Wang Jun is second; Weiping third
3. Omission
4. Wrong and wrong.
5, 12*6=72 square meters
72*95=6840 yuan; 72*65=4680 square meters
6840-4680=2 160 yuan
Exercise the brain.
(1)8:00 to 14:00 6 hours later; 540/6 = 90km
(2) from14 to 2 o'clock after 12; 12 * 90 =1080km
(3) 18 hours later 12: 00 to 20: 45;
18 hours 45 minutes+12 hours +6 hours =36 hours 45 minutes.
At 6: 30, after 36 hours and 45 minutes to 43: 00, 15 minutes = 65438+ 09: 00 the next day.
Page 22-23
1、8 100; 500; 440; 30
100; 1; 600; 6.8
3200; 90; 500; 500
3600; Iv ..... 4; 400; Fifty-six
2、5 1;
7;
7; three
4; three
3、5*200= 1000; 5* 123=6 15; 5* 16=80
5*50=250 5*800=4000; 5*9=45; 5*306= 1530
4、4; 6; seven
7; 7; three
5,3 * 2 * 3 =18 (Ben)
6. 120/3/2=20 (days)
Exercise the brain.
Length 1 2cm, width1cm. The circumference is 26 cm.
6 cm long and 2 cm wide. Circumference16cm
4 cm long and 3 cm wide. Circumference 14cm
P24-25
1, omitted
2、2/5; 3/5
6/7; 1/7
5/9; 4/9
3、5;
4; 1
nine
4. Omission
5, 9* 12= 108 (yuan)
68*5=340 cm
22 * 3+22 = 88m
Exercise the brain.
36 * 5 = 180g
180/2 = 90g
9 * 5 = 450g
Page 26-27
1, omitted
2. Omission
3. The product greater than 2000 is 97 * 53; 69*38; 29*79
The remaining products are less than 2000.
4. Omission
5、 104; 1 12......4; 73...... 1
Exercise the brain.
8 1
Page 28-29
1, omitted
2、 630; 172; 904; 165; 963; 88
3. Anyway
4, one point zero eight; 0.0005; Thirteen twenty-six; 18.69
5、 12:00; 12:30; 13:00; 13:30
6.( 1) 3577-2250 = 1327m
(2)5400-3000=2400 meters
Use your head:
( 1)9
(2) 500 respectively; 2; three
P30-3 1
1, omitted
2、 199; 5687; 722 1
3、465; 993
930; 963
4. 1 10 meter hurdles; Read a line; Oral arithmetic competition; The answer to the knowledge contest; Blank time of aircraft model, etc.
5, (1) 576/6,8 =12 yuan.
(2)96/8*24=288 yuan
Exercise the brain.
15/3=5 times
(3+2)*5=25
25-2=23 o'clock
P32-33
1, omitted
2. Evening 10:52
20: 15; Fifteen to three/a quarter to three
15:37; 10:2 1 morning
3. 19*8 is about = 160 yuan.
39*5 =200 yuan, that's enough.
3,000 tons; kilogram
g； Scold or fight?
Tons; Scold or fight?
5. 15*3=45 yuan; 37*2=74 yuan
leave out
Use your head:
4+3+2+ 1= 10 times
P34-35
1, omitted
2.( 1) 2; Three, five; Fourth; one
(2) 4; Second; One; Third; five
(3) 2; Third; Fourth; One; five
3.( 1) North; South; western
(2) South; North; east
(3) west; East; south
4. (1)17 * 21is about 400.
(2) Omission
5. Use your head.
* * * Four situations: A is black before B; A front and b white; A reverse and b black; A reverse and b white. Therefore, it is fair.
P36-37
1、400; 1 1; 1800; 900
200; 1.5; 400; 555
1; 5......3; 900; 3.7
2、
How many sets are there? 1544+63= 1607 sets
How many units were sold? 2480-63=24 17 sets
How many sets are left? 2480- 1540=940 sets
3. Pay attention to the parallelogram.
4. Omission
Use your head:
5; Forty-four
P38-39
1\ 1200; 40; 200; 1600
304; 3600; 0; 600
6300; 33; 48; 1000
420; 32; 6......6; 1200
2、32; 136.......3; 14...... 1; 180...... 1
3. Omission
4、(2)304; 302
(3) (160+140+100+120)/4 =130 (yuan)
(4) Omission
5、( 1) 1,2; (2) 26,25
(3)5,6; (4)5 1,50
6. Use your head
Pay attention to draw a schematic diagram before calculation.
Circumference:1* 4 * 4 =16cm;
Minimum circumference: 1 * 2 * 4 = 8cm.
P40-4 1
1, omitted
2、 14. 1; 5.6; 1.9
15.3; 5.9; 13. 1
3. Omission
4、6, 1; 5,2; 4, 1; 2,2
Use your head:
(7+6+5)/2=9 (kg)
P42-43
1, omitted
2、0.6; 2 tons and 300 kilograms
2.8
3.( 1) The second starting line is the longest; Galaxy Theater is the shortest.
(2)30- 10=20 points
(3)19: 00-17: 30 =1hour 30 minutes.
4.( 1) 65/5 = 13m
(2) 5 * 5 = 25m2
(3)13-5 = 8m 8 * 5 = 40m2
(4) (8+5)*2=26 meters
Use your head (1) rectangle: 7*4=28 square centimeters; Square 4*4= 16 square meters
(2) Divide the effect square with straight lines. A=20 pieces; B= 19 yuan
P44-45
1, omitted
2、8.2; 8.6; 14. 1
4.3; 2.2; 4.9
3. Wrong 2539; Error1564; Cuo 13
4. Omission
Five out of 5/91/9; 1/5 contains 1 1.
6, the number is less than 500: 2, 3, 4, 7.
The number is between 500- 1000: 6.
The score is greater than 1000: 1, 5.
Use your head:
8585=425, 82*3+90=336, 425-336=89.
46-47
1, omitted
2, 9 cm long, width 1 cm; 8 cm long and 2 cm wide; 7 cm long and 3 cm wide; 6 cm long and 4 cm wide; 5 cm long and 5 cm wide.
3 、& lt,=;
& lt,=
4293 points
272 points
249 points
About 89 minutes and 90 minutes; 92 points; About 27 1 min
5. (1)12 * 6/6 =12 boxes
(2) 2 hours from 8: 00 to 10.
(3) 75 * 2 =150km
150 > 145, yes.
(4) 12/4 = 3m( 12+3)* 2 = 30m。
Exercise the brain.
There are 40 people in all four corners; 20 people in the middle of each side
P48-49
1、6700; 800; 200; 5200
600; 2800; 1.7; 5400
60; 6400; 18; Forty nine
8000; 7/9; 4200; 630
2\ 13: 15 - 14: 15
14:30 - 15:30
15:45 - 16:45
17:00 - 18:00
3\ 5 or 6 or 7 or 8 or 9; four
1. 1 6,3
9 5 or 6
4 or 2 times; (20+ 10)* 2 = 60mm； 3 times, 12 * 2+8+ 16 = 48mm.
Quantity 1 time, 12 * 4 = 48mm.
2 times, (15+ 19) * 2 = 68mm.
5. There are many answers:1/6; 3/7; 1/6
2/9; 1/8; 1/5
4/5(); 2/2,4/4,5/5,6/6
6. Use your head
( 1)a=6
(2)76 meters
P50-5 1
1、800; 6900; 3600; Eight hundred
1000; 40; 2/3; 60
0; 7200; 4.。 . . . . 5; 360
3600; 490; 0; 3000
2、 187; 840; Bai 83
45; 24; 6 1
3、 1545; 1537; 48......3
4、 17;
seven
2 1,7
5.( 1)40 * 8 = 320m； 320+486=806 meters
(2) 389 * 2 = 778m
(3) 320 * 3+63 = 1023m
Think about 3+5=8 400/8 = 50g 50 * 2 = 100g.
400-100 = 300g 300/2 =150g
P52-53
1\LUE
2. 18 species
3、 1 134; 344; 5382; 104
4. Rabbit speed 5 * 4 = 20m.
Distance of tortoise: 5 * (4+ 16) = 100m.
Distance the rabbit ran: 20 * 4 = 80m.
The distance a rabbit should run: 100-80 = 20m.
Exercise the brain.
(1) Product 4 1*32
Minimum 13*24
(2) (30+2+2) * (15+2+2) = 646m2.
30 * 15 = 450m2
646-450 =196m2
P54-55
1, omitted
2、4, 1; 1,6
2,4; 3,4
3. Anyway
4、33; 46;
28; 524
56 1; leave out
10; nine
5、 1600; 1 170; 9 100; 528
4500; 567; 1008; 1978
Think: 2 1978*4=879 12.
P56-57
1\LUE
2、30000; 2
440
3. Omission
(12+8) * 2 = 40cm 40/4 =10cm10 *10 =100 cm2.
5. (1) (240+260+280)/3 = 260 sets; (240+280+320)/3=280 sets
280-260=20 sets
(2) A: B is growing rapidly. Maybe B air conditioner is of good quality and cheap price.
Use your head: 7
P58-59
1\LUE
2、275
240
3、0.8; 1.25
0.8; 5.4
0.5; 0.4
(1) 48 * 5 = 240 bits
(2) 12*5=60 cm2 3*3=9 cm2 6 0-9=5 1 cm2.
10 block is 3cm long and 2cm wide, and 4 blocks are placed horizontally; 2 cm long, 3 cm wide, 6 pieces horizontally.
Think: 1972 2 about 29 days.
P60-6 1
1\ LUE
2\ 1227; 629; 18 13; 304
3\ LUE
4\
(1) 10*2=20 yuan (23- 10)*3=39 yuan.
39+20=59 yuan
(2) 94/4 = 24km180-96 = 84km.
24 * 2 = 48km is no good.
Use your head17; 22; 29