3.P9 wheat is placed in the 28th grid, which has exceeded 654.38+0 billion grains; About 92233720368 million tablets will be put in the 64th box.
4. From P 1 1, 3 and 4 are wrong, and the rest are right.
5. Degree of angle p 15: angle 4=60 degrees, angle 5=72 degrees and angle 6=36 degrees.
6.P 19, draw a picture, pay attention to draw a vertical line and mark it with rectangular symbols.
7, P20, trapezoid has 5 and 6, and the axisymmetric figure is 1, 3, 4, 5.
8.P23 Fill in 1 m2 =0.036 hectares.
Receipt: RMB 38,650.00 in words.
9.P24 Select (3) Select 9.
10, P3 1 Think about it (1) Choose A and B.
1 1, P43 matching formula: 23x4 = 92 28x11= 30817x14 = 238.
The formulas of 12 and P45 are 209x46 = 9614372x38 =141315x41=129/kloc-0.
13, the outermost layer of P47 to solve the problem: (10- 1)x4=36 (basin) a * * *10x10 =100 basin.
Draw a picture and calculate (21-1) x50 =1000 cm =10m (260+10)/37 =/kloc-.
The numbers of 14 and P50 are 12, 16 and 12 respectively.
15, P53 14th century, China people.
16, P55 solving problems 142-34= 108 (block) 108/2=54 (block) 54/ 18=3 (times)
17, P56 formula calculation (3) difference: 75- 15=60 Kobayashi is 60/(3- 1)=30 years later: 30- 15= 15 years later.
18, P58 Fill one and fill two (5) and add (5) zeros in the middle of 48 to get 400 0008.
19 and P60 2 are filled in the table, and the dividend and divisor are expanded by the same multiple (except 0) at the same time, and the quotient remains unchanged.
20, P6 1 think about it. (3) It obviously took 2.5 hours to ride a bike, with an average of 12 kilometers per hour.
1. True or false
(1)× (Water can dissolve some solids, as well as gases and liquids. )
(2)× (Rock sugar still exists after it is dissolved in water. )
Put some lard in the hot vegetable soup, and it will break down into smaller ones. )
(4) When the water evaporates, the substances dissolved in the water still exist. )
(5)× (Insoluble substances may not all sink to the bottom when put into water. For example: vegetable oil. )
(6)√
(7)√
Sound can travel in water. )
Sound can travel in all directions. )
(10)√ (no air transmission)
2. Insolubles are: flour, rape and clods.
3. Small experiment
Tip: Try to put as much salt as possible when doing small experiments, and choose bottles with as small a mouth as possible, so that the observation results will be more obvious.
The results show that the water level rises obviously when the salt content is large and the bottle mouth is small. If the salt content is small and the bottle mouth is large, the water level will not rise obviously, but it will rise in principle and the water level will also rise.
4. I hope to read the content of the small materials carefully and talk about it in practice.
Page 64
1. Multiple choice problem
( 1)C (2)A (3)C (4) C
2. True or false
All seven questions are √.
Explain question (3): (Pay attention to the difference)
Connecting two batteries in series can make the bulb emit brighter light.
Connecting two bulbs in series can make the small bulb emit darker light.
3. Small experiment
(1) Explaining the principle of homemade wind instruments
Test tube: the water level is low, the test tube vibrates quickly and the sound is high. On the contrary, the water level is high, the test tube vibrates slowly and the sound is low. (The figure should show bass. )
Suction pipe: short air column, fast vibration and high sound; Long air column, slow vibration and low sound. The picture should be high and low. )
(2) Small activities
The brine heating bulb turns bright and the brine cooling bulb turns dark. The reason is that the increase of salt water temperature accelerates the molecular activity, and the electrolyte in water increases, which increases the conductivity of water.
extreme
1).
(1)45 times 102=45 times 100 plus 45 times 2 is a simple calculation using multiplication and division.
(2) In the formula without brackets, if there is only addition and subtraction or only deviation, it should be calculated from (left to right. But if you only do addition or multiplication, you can also count the pairs first)
(3) Multiply any number by 0 to get (0). When 0 is divided by a non-zero number, the quotient is (0).
2) In what order are the following questions calculated?
(1) When calculating that 75-45 is divided by 5, you should first calculate (divide) and at the same time calculate (subtract).
(2) When dividing (75-45) by 5, the calculation (subtraction) should be made first, and at the same time the calculation (subtraction) should be made.
(3) When calculating 75-45+5, first calculate (divide) and then calculate (add).
3) Divide the formula 60-24+30 by 6 and add brackets as needed to calculate.
(1) Calculate subtraction first, then addition, and finally division.
(60-24+30) divided by 6
(2) Add first, then divide, and finally subtract.
60-(24+30) divided by 6
(3) Calculate division first, then addition, and finally division.
(60-24+30) divided by 6
5)( 1) 232-54+68=246 232+(68-54)=246
(2) 420 divided by 6*30 =2 100, how many bees are brewed in one box and how many bees are brewed in 30 boxes.
420 * 30 divided by 6 = 2100 How many 6 boxes are there in 30 boxes?
(3) Class 4 (2) is 48 * * 6 = 40 * 6+8 * 6 = 240+48 = 288.
288-268=
(4) Three months in a quarter, 90*3=270.
270-( 1 14+76)=
6) I am an expert at deciphering.
Big white box =43 black triangles =26 big white triangles =93 small black boxes. 14
4326 93 14
P3
3) How to simply calculate the following questions?
450-225 divided by 5+ 135 25*7 1*4.
=450-45+ 135 = 100*7 1
=405+ 135 =7 100
99*425 304+306 divided by 17-298
=42500-425 =300-298+4+ 18
=42075 =2+4+8
101* 79-79 (6409+23 *17) divided by 68.
=100 * 79+79 *1-79 = (6409+391) divided by 68.
4) ( A+B )*(E-F)=G
5) Solve the problem
Pear =204 divided by 3=68 peach =68 times 2= 136 peach.
204+68+ 136=
20 yuan in Grimm's Fairy Tales and 8 yuan in Science Stories cost 1 16 yuan. How many books did you buy each?
Solution idea 1 Divide the unit price of A by the total price and you will get a remainder. Multiply this remainder by the unit price of A until it is equal to the unit price of B. ..
Solution 1 1 16 divided by 8 = 14. . . . four
4+2*8=20 4+7*8=60 4* 12*8= 100
14-2= 12 14-7=7 14- 12=2
So there are three ways to buy.
1 grimm fairy tale, stories of 5 scientists, stories of 2 scientists.
Two grimm's fairy tales, three stories of scientists and seven stories of scientists.
3 grimm's fairy tale 1, scientist's story 12.
Solution 2 1 16 divided by 20 =5. . . 16
2 times 8 =1616+2 * 20 = 5616+4 * 20 = 96.
A So there are three ways to buy.
1 grimm fairy tale, stories of 5 scientists, stories of 2 scientists.
Two grimm's fairy tales, three stories of scientists and seven stories of scientists.
3 grimm's fairy tale 1, scientist's story 12.
The problem-solving idea 2 1 16 is decomposed into a number divisible by 20+ remainder.
* * * can be divided into the following categories
100 + 16 80+36 60+56 40+76 20+96
The remainder divisible by 8 is 16 56 96.
So there are three ways to buy.
1 grimm fairy tale, stories of 5 scientists, stories of 2 scientists.
Two grimm's fairy tales, three stories of scientists and seven stories of scientists.
3 grimm's fairy tale 1, scientist's story 12.
The mystery of P4 surname
The students of the four teachers are surnamed Zhao, Wang, Chen and Wu respectively.
1 Start with Teacher Zhao: Teacher Zhao's students may be surnamed Wang, Chen and Wu.
Now we know that the students present are Chen and Zhao.
Start with Mr. Wang and Mr. Zhao. Mr. Wang's students didn't come, so Mr. Wang's students may be surnamed Wang or Wu.
It is known that teachers and classmates have different surnames, so Mr. Wang's students will only be surnamed Wu.
The classmate surnamed Wu is a student of Mr. Wang, so there are only students of Mr. Zhao, Chen, Wang, Zhao and Chen. The conversation shows that Chen is not a student of Miss Zhao, so Miss Zhao's student's surname is Wang.
This can be obtained.
Miss Zhao-Miss Wang-Miss Wang-Miss Wu,
The others are Mr Wu, Mr Chen, Mr Zhao and Mr Chen.
So Mr. Wu-classmate Chen-classmate Chen-classmate Zhao.
A: So four teachers correspond to four students.
Miss Zhao-Miss Wang-Miss Wang-Miss Wu
Mr Wu-Mr Chen-Mr Zhao.
P5 1) Can you quickly calculate the results of the following questions?
3 12- 155-45=3 12-( 155-45)=3 12- 10=302
125 * 23 * 8 = (125 * 8) * 23 =1000 * 23 = 23,000 knowledge points,
Extension 25 * 4 =100 25 * 8 = 200125 * 4 = 500125 * 8 =1000 study hard.
2400 divided by 25 divided by 4=600 divided by 25=24
89*99+89=89* 100=8900
3) Calculation by simple method
199*490=200*490-490=98000-490=975 10
256*30 1=256*300+256=76800+256=77056
457*48+457*52=457*(48+52)=45700
16*( 125*34+88* 125)= 16* 125*34+ 16* 125*88
=2000*34+2000*88=2000* 122=2440000
4)( 1) 143*5+ 143*6+ 143*9= 143*(20)
P6 5 Solve the problem
(1) Apple = 25-5 = 20kg
(20+25)*8=45*8=360 kg
(2)( 20*23+ 18)*60=3480 (km)
(3) 2000/25 * 8 = 2000/200 =100 (yuan)
(4)432/(20- 12)=432/8=54 (yuan)
6) Use your head
Let a be X.
Then the age of B ==x-6, and the age of C ==2x.
Age of C = x-6+22
2x = x-6+22 2x = x+ 16 x = 16
The age of A is 16, the age of B is 10, and the age of C is 32.
16+ 10+32=58
Select 1) 4 2) 2 3) 3 4)
2) What have you gained by comparing the results?
84-23- 15=46 54/9*3= 18
84-23+ 15=76 54/(9*3)=2
84-(23+ 15)=46 54/(9/3)= 18
Tisso
1, 1, (950,994,650), (95099),( 10)
2, (80500006), 3, (yellow ball) 4, (pointed), (blunt) 5, (350+400)÷5= 150.
6, blunt 105 sharp 75 flat 1807, (CE or C)8, (a×b)×c=a×(b×c)
9, (1 degree), (1 degree) 10, (3)?
1，B2，C3，B4，C5，A？
3. √××××?
Iv. 1, omitted 2,10070034 ...152003, 27009 129300 V.?
6. 1, omitted 2, 3 13 (tree) 3, 32 (root) 4, 12 (hour) 5, 22 (year) 6, omitted.
11.400 million; 2, 136000003,2,307,260,000;
324.74 billion 635.2 billion
4.1300 million >103 million > 89760000 & gt 10/00000.
5, 1,2; 6,67,3
2, 1, C2, A3, B4, C5, B.
3, 1, × 2, × 3, × 4, √ 5, ×
IV. (Omitted) V. (Omitted)
6. 1 7600, 12040, 18468,1815,4725, 10000.
2,7000,600,287 1,4600,5290,780
Seven, 1.54 million yuan; 23 198 yuan; 3,470 yuan; 4 1650 yuan;
586 meters, 8428 yuan