Bitcoin crazy
Publish: 2021-04-23 19:56:55
1.
The decline and rise of bitcoin are normal phenomena, because it is a kind of virtual currency. Since it is a virtual currency, it is bound to rise and fall, just like stocks. Personally, I don't think it's cutting leeks, because bitcoin is a virtual currency. As we said earlier, there are ups and downs. This is the law of development of things
bitcoin is like this. We should understand it first, and then make a judgment. This is the most important thing. The learning before the exam is the judgment, and the result of the exam is the gain. And those who have not learned, of course, can not enjoy themselves, so I personally think the crazy fall and rise of bitcoin is a normal phenomenon. Of course, this is only my personal understanding, not the public opinion
2.
Bitcoin can be said to be the ancestor of virtual currency. It was launched in 2009. At that time, the value of bitcoin was very low. One dollar could buy more than 1300 bitcoins. At that time, a programmer in the United States exchanged 1000 bitcoins for two pizzas, which is often ridiculed by everyone. A lot of people are saying that if his bitcoin had been preserved until now, he would have been a billionaire. But who knew that bitcoin would be so valuable in modern times? At that time, few people knew about bitcoin, so there was no hype. At that time, bitcoin had no economic purpose. It was just used to exchange game equipment
now the world uses a lot of electricity to dig bitcoin every year, because the cost of electricity is very high, and the market value of bitcoin is volatile, so the benefits obtained by digging bitcoin are very small
3. Manual shooting skills of SLR camera
1. Take close-up pictures of small still objects, such as flowers, birds and insects:
use AV file, the aperture should be f5.6 or below, the focal length should be more than 50, and try to shoot within 1m to make the background virtual
if the light is good, ISO 100, if the light is bad, ISO should be within 400<
2. Shooting people:
basically use a large aperture (within f5.6) and a focal length of more than 50 mm. The shooting distance depends on the whole body, half body and big head, which makes the background virtual. Use AV file
good light, iso100, bad light, iso400
people in motion use tracking to reflect the sense of motion (see the shooting of moving objects below for details)<
3. Shooting:
AV file, use the appropriate aperture, above F8, the focal length is arbitrary, but generally the wide-angle end has distortion, use it as appropriate<
4. Shooting night scene:
upper tripod, AV gear, custom white balance or incandescent lamp, aperture above F8, small aperture can make the light proce starlight effect, use the reflector pre rising function to rece the vibration caused by the reflector lifting after pressing the shutter; And cover the viewfinder with the square cover on the strap to prevent stray light from entering from the back and affecting the image quality; ISO 200, as far as possible to make the exposure time longer, so that some people who have no intention to walk away from the screen disappear, leaving no traces, clean the scene
for example, when taking a square with people coming and going, you can use a very small aperture of about F20 and iso100. In this way, the exposure time will be very long, and the moving figures will not stay in the photos! The square will be clean<
5. Shooting fireworks:
using shutter line and B shutter, you can shoot multiple fireworks overlapping effect<
6. Shooting things:
when the light is good: AV, the aperture size should be handled according to the circumstances; Large depth of field can be obtained by using aperture above F8, and shallow depth of field can be obtained by using small aperture
if you want to have a very dynamic effect, you can use the TV gear, the shutter is about 1 / 30, when you focus and press the shutter, the lens will follow the object at an appropriate speed, which will proce a very dynamic effect
poor lighting: we can only handle it according to our own discretion, plus use the follow-up camera<
7. Shooting running water or fountain:
using TV and about 1 / 50 shutter speed, you can shoot Satin effect. If you use too fast shutter speed, the fountain will shoot discontinuous water drops<
8. Taking photos at night:
use tripod to adjust white balance, and automatically or custom white balance; iso100-400 AV gear, aperture about F8, use slow synchronous flash, rear curtain flash mode; At this time, the flash will flash twice, press the shutter to flash once, and flash again before the end of exposure, so don't leave before flashing twice
in this way, the characters can be clear and the background neon is beautiful, so that the background will not be too dark e to insufficient exposure< No matter what you shoot, don't shoot with the maximum aperture unless you want to keep a safe shutter
2. Please use the aperture of F8 ~ F11 as much as possible when shooting scenery
3. The maximum aperture can be reced by 1-2 levels when taking close-up of people and still life
4. The safety shutter should be controlled above the reciprocal of the focal length as far as possible. The wide-angle shutter should also be more secure at more than 1 / 30 second. If the shutter is insufficient, please increase the aperture or ISO<
metering method:
1. Don't measure the light to the sky or the darkest place. Go to the middle value
2. According to your subject matter, make good use of the metering mode (balance metering, point metering, central key metering...)
3. If the light measurement is not accurate, please use AE lock to expose and lock the gray things around you before shooting
4. Try not to measure the light on white or black objects, otherwise remember to rece eV for black and increase eV for white<
EV is exposure compensation.
exposure compensation is also an exposure control method, which is commonly used in ± If the ambient light source is dim, the exposure value (such as + 1eV, + 2eV) can be increased to highlight the clarity of the picture
most of the small digital cameras adjust the exposure compensation through the menu
in the process of shooting, if you press half of the shutter, the LCD will display pictures similar to the final effect picture, focusing and exposure will start. The exposure at this time is exactly the exposure of the final picture. If the picture is obviously bright or dark, it means that the automatic metering accuracy of the camera has a large deviation, and the exposure compensation should be enforced, but sometimes the brightness displayed ring shooting is different from the actual shooting result. Digital camera can browse the picture immediately after shooting, at this time, you can more accurately see the brightness of the picture, there will be no difference. If the shooting result is obviously bright or dark, it is necessary to re shoot and force the exposure compensation
the shooting environment is dim, and the brightness needs to be increased. When the flash cannot work, the exposure can be compensated and the exposure can be increased appropriately. For exposure compensation, if the photo is too dark, increase the EV value. Every 1.0 increase in EV value is equivalent to doubling the amount of light intake. If the photo is too bright, decrease the EV value. Every 1.0 decrease in EV value is equivalent to doubling the amount of light intake. The compensation interval can be adjusted in 1 / 2 (0.5) or 1 / 3 (0.3) units according to different cameras
when the white object to be photographed looks gray or not white enough in the photo, it is necessary to increase the exposure. In short, "the whiter the object is, the more white the object is." this seems to run counter to the basic principles and habits of exposure. In fact, it is not. This is because the main body of the camera is often the center of the light measurement, and the White main body will make the camera mistakenly think that the environment is very bright, As a result, the exposure is insufficient, which is also a common problem for most beginners
because the shutter time or aperture size of the camera is limited, it is not always able to reach the 2eV adjustment range, so the exposure compensation is not omnipotent, and it may still be underexposed in too dark environment. At this time, it is necessary to consider cooperating with the flash or increasing the ISO sensitivity of the camera to improve the brightness of the picture
generally speaking, the smaller the brightness contrast of the scene, the more accurate the exposure, otherwise, the larger the deviation. The grade of the camera is high and low. If the grade is high, the metering is more accurate, and if the grade is low, the deviation will be increased. If it is a traditional camera, the tolerance of film is relatively large, and the exposure deviation will not have a big problem within a certain range, but the CCD tolerance of digital camera is relatively small, and slight exposure deviation may affect the overall effect
in a word, the adjustment of exposure compensation is determined by experience and sensitivity to color. Users must compare the image quality, clarity, restoration degree and noise size under different exposure compensation to get the best picture
note:
the aperture in Canon's manual refers to the F value. The larger the aperture, the greater the depth of field
generally speaking, aperture refers to aperture, which is inversely proportional to F. the larger the aperture, the smaller the depth of field
AV -- aperture priority auto exposure
TV -- shutter priority auto exposure
AE auto exposure
AF auto focus
AF-S -- single auto focus, the same as saf. The opposite is continuous autofocus
MAF - monitor AF, which can shorten the focusing time. The camera will adjust the focus before half pressing the shutter button, so that you can compose with the adjusted focus. When the shutter button is half pressed and AF locking is completed, the focus will be locked
ev - exposure value, which is usually used in exposure compensation
ISO sensitivity. Each difference of sensitivity is equivalent to the corresponding exposure value of aperture or shutter
brother, if you have time, go to ZhongGuanCun video forum and see the forum.
1. Take close-up pictures of small still objects, such as flowers, birds and insects:
use AV file, the aperture should be f5.6 or below, the focal length should be more than 50, and try to shoot within 1m to make the background virtual
if the light is good, ISO 100, if the light is bad, ISO should be within 400<
2. Shooting people:
basically use a large aperture (within f5.6) and a focal length of more than 50 mm. The shooting distance depends on the whole body, half body and big head, which makes the background virtual. Use AV file
good light, iso100, bad light, iso400
people in motion use tracking to reflect the sense of motion (see the shooting of moving objects below for details)<
3. Shooting:
AV file, use the appropriate aperture, above F8, the focal length is arbitrary, but generally the wide-angle end has distortion, use it as appropriate<
4. Shooting night scene:
upper tripod, AV gear, custom white balance or incandescent lamp, aperture above F8, small aperture can make the light proce starlight effect, use the reflector pre rising function to rece the vibration caused by the reflector lifting after pressing the shutter; And cover the viewfinder with the square cover on the strap to prevent stray light from entering from the back and affecting the image quality; ISO 200, as far as possible to make the exposure time longer, so that some people who have no intention to walk away from the screen disappear, leaving no traces, clean the scene
for example, when taking a square with people coming and going, you can use a very small aperture of about F20 and iso100. In this way, the exposure time will be very long, and the moving figures will not stay in the photos! The square will be clean<
5. Shooting fireworks:
using shutter line and B shutter, you can shoot multiple fireworks overlapping effect<
6. Shooting things:
when the light is good: AV, the aperture size should be handled according to the circumstances; Large depth of field can be obtained by using aperture above F8, and shallow depth of field can be obtained by using small aperture
if you want to have a very dynamic effect, you can use the TV gear, the shutter is about 1 / 30, when you focus and press the shutter, the lens will follow the object at an appropriate speed, which will proce a very dynamic effect
poor lighting: we can only handle it according to our own discretion, plus use the follow-up camera<
7. Shooting running water or fountain:
using TV and about 1 / 50 shutter speed, you can shoot Satin effect. If you use too fast shutter speed, the fountain will shoot discontinuous water drops<
8. Taking photos at night:
use tripod to adjust white balance, and automatically or custom white balance; iso100-400 AV gear, aperture about F8, use slow synchronous flash, rear curtain flash mode; At this time, the flash will flash twice, press the shutter to flash once, and flash again before the end of exposure, so don't leave before flashing twice
in this way, the characters can be clear and the background neon is beautiful, so that the background will not be too dark e to insufficient exposure< No matter what you shoot, don't shoot with the maximum aperture unless you want to keep a safe shutter
2. Please use the aperture of F8 ~ F11 as much as possible when shooting scenery
3. The maximum aperture can be reced by 1-2 levels when taking close-up of people and still life
4. The safety shutter should be controlled above the reciprocal of the focal length as far as possible. The wide-angle shutter should also be more secure at more than 1 / 30 second. If the shutter is insufficient, please increase the aperture or ISO<
metering method:
1. Don't measure the light to the sky or the darkest place. Go to the middle value
2. According to your subject matter, make good use of the metering mode (balance metering, point metering, central key metering...)
3. If the light measurement is not accurate, please use AE lock to expose and lock the gray things around you before shooting
4. Try not to measure the light on white or black objects, otherwise remember to rece eV for black and increase eV for white<
EV is exposure compensation.
exposure compensation is also an exposure control method, which is commonly used in ± If the ambient light source is dim, the exposure value (such as + 1eV, + 2eV) can be increased to highlight the clarity of the picture
most of the small digital cameras adjust the exposure compensation through the menu
in the process of shooting, if you press half of the shutter, the LCD will display pictures similar to the final effect picture, focusing and exposure will start. The exposure at this time is exactly the exposure of the final picture. If the picture is obviously bright or dark, it means that the automatic metering accuracy of the camera has a large deviation, and the exposure compensation should be enforced, but sometimes the brightness displayed ring shooting is different from the actual shooting result. Digital camera can browse the picture immediately after shooting, at this time, you can more accurately see the brightness of the picture, there will be no difference. If the shooting result is obviously bright or dark, it is necessary to re shoot and force the exposure compensation
the shooting environment is dim, and the brightness needs to be increased. When the flash cannot work, the exposure can be compensated and the exposure can be increased appropriately. For exposure compensation, if the photo is too dark, increase the EV value. Every 1.0 increase in EV value is equivalent to doubling the amount of light intake. If the photo is too bright, decrease the EV value. Every 1.0 decrease in EV value is equivalent to doubling the amount of light intake. The compensation interval can be adjusted in 1 / 2 (0.5) or 1 / 3 (0.3) units according to different cameras
when the white object to be photographed looks gray or not white enough in the photo, it is necessary to increase the exposure. In short, "the whiter the object is, the more white the object is." this seems to run counter to the basic principles and habits of exposure. In fact, it is not. This is because the main body of the camera is often the center of the light measurement, and the White main body will make the camera mistakenly think that the environment is very bright, As a result, the exposure is insufficient, which is also a common problem for most beginners
because the shutter time or aperture size of the camera is limited, it is not always able to reach the 2eV adjustment range, so the exposure compensation is not omnipotent, and it may still be underexposed in too dark environment. At this time, it is necessary to consider cooperating with the flash or increasing the ISO sensitivity of the camera to improve the brightness of the picture
generally speaking, the smaller the brightness contrast of the scene, the more accurate the exposure, otherwise, the larger the deviation. The grade of the camera is high and low. If the grade is high, the metering is more accurate, and if the grade is low, the deviation will be increased. If it is a traditional camera, the tolerance of film is relatively large, and the exposure deviation will not have a big problem within a certain range, but the CCD tolerance of digital camera is relatively small, and slight exposure deviation may affect the overall effect
in a word, the adjustment of exposure compensation is determined by experience and sensitivity to color. Users must compare the image quality, clarity, restoration degree and noise size under different exposure compensation to get the best picture
note:
the aperture in Canon's manual refers to the F value. The larger the aperture, the greater the depth of field
generally speaking, aperture refers to aperture, which is inversely proportional to F. the larger the aperture, the smaller the depth of field
AV -- aperture priority auto exposure
TV -- shutter priority auto exposure
AE auto exposure
AF auto focus
AF-S -- single auto focus, the same as saf. The opposite is continuous autofocus
MAF - monitor AF, which can shorten the focusing time. The camera will adjust the focus before half pressing the shutter button, so that you can compose with the adjusted focus. When the shutter button is half pressed and AF locking is completed, the focus will be locked
ev - exposure value, which is usually used in exposure compensation
ISO sensitivity. Each difference of sensitivity is equivalent to the corresponding exposure value of aperture or shutter
brother, if you have time, go to ZhongGuanCun video forum and see the forum.
4.
The concept of bitcoin was first proposed by Nakamoto on November 1, 2008, and was officially born on January 3, 2009. According to the idea of Nakamoto, the open source software is designed and released, and the P2P network on it is constructed. Bitcoin is a virtual encrypted digital currency in the form of P2P. Point to point transmission means a decentralized payment system
unlike all currencies, bitcoin does not rely on specific currency institutions. It is generated by a large number of calculations based on specific algorithms. Bitcoin economy uses the distributed database composed of many nodes in the whole P2P network to confirm and record all transactions, and uses the design of cryptography to ensure the security of all aspects of currency circulation
the decentralized feature and algorithm of P2P can ensure that it is impossible to artificially control the value of bitcoin by mass manufacturing. The design based on cryptography can make bitcoin only be transferred or paid by the real owner. This also ensures the anonymity of money ownership and circulation transactions. The biggest difference between bitcoin and other virtual currencies is that the total amount of bitcoin is very limited and it has a strong scarcity
extended information:
users can buy bitcoin, and at the same time, they can also use computers to "mine" bitcoin according to a large number of calculations. When users "mine" bitcoin, they need to use the computer to search for 64 bit numbers, and then compete with other gold miners by repeatedly solving puzzles to provide the required numbers for the bitcoin network. If the user's computer successfully creates a set of numbers, then they will get 25 bitcoins
e to the decentralized programming adopted by the bitcoin system, only 25 bitcoins can be obtained every 10 minutes, and by 2140, the maximum number of bitcoins in circulation will reach 21 million. In other words, bitcoin system is able to achieve self-sufficiency, resist inflation through coding, and prevent others from destroying these codes
5. The earliest one is around 6 a.m., running water, usually half an hour to an hour
about three hours to Puyang
about three hours to Puyang
6. Bitcoin is a kind of virtual currency. It uses a specific computing method of graphics card to download and install a program on the computer. It doesn't need to be watched and works 24 hours a day. It is a particularly intelligent operation. Now a bitcoin can be sold for 20000 yuan, but the graphics card configuration is particularly high. My configuration is in a good cow it there to buy, there are also technical personnel to install for you! I hope my answer will help you!
7. The cultivation of computational ability is an important task in primary school mathematics teaching. The level of a person's computing ability is the embodiment of his thinking agility and thinking flexibility in computing, which reflects the level of his basic mathematical quality. The level of computing ability not only affects students' academic performance, but also directly affects students' intellectual development, and also has a direct impact on students' future study and work. In the primary school stage, the main purpose is to cultivate students' ability to calculate integers, decimals and fractions, and to achieve correct and rapid calculation. At the same time, the method is required to be reasonable and flexible. How to cultivate and improve students' computing ability to meet the above requirements
in this paper, I would like to talk about some superficial understanding of this problem< First, we should fully understand the importance of developing computing ability
one of the aims of primary school mathematics teaching is to cultivate students' computational ability, and teachers must have enough understanding. Some teachers don't pay enough attention to the cultivation and improvement of students' computing ability, and they don't let students find the rules and interests of computing. This is a big obstacle to cultivate and improve students' computing ability, which must be removed. Computational ability is a necessary ability for students< Number and calculation are widely used in daily life, work and study. In the real world, from the perspective of mathematics, there are mainly three aspects: number, quantity and shape. However, measurement is inseparable from number and calculation, and the quantification of body size is inseparable from number and calculation. Therefore, number and calculation are the most basic tools for people to understand the objective world and the basic knowledge and skills that every citizen should master< Number and calculation are the basis for students to learn other mathematical knowledge and even other subjects. This part of the knowledge is not good, students can not enter the normal learning< Number and calculation play an important role in cultivating students' thinking ability. Mastering the process of number and calculation is also the process of cultivating students' abstract generalization ability. In this way, students also develop the ability of abstract generalization in the process of learning to master the knowledge of number and calculation
4. The teaching of number and calculation is concive to infiltrating the enlightenment ecation of dialectical materialism. The concept of number is graally formed and developed with the needs of human life and practice. When teachers want to teach the concept of number, the relationship between calculation method and calculation method, they can infiltrate the enlightenment ecation of dialectical materialism
Second, clarify the calculation theory and improve the teaching quality of calculation
in the teaching of calculation, teachers should pay attention to explain the principle of calculation and reveal the law of calculation, so that students can know what it is and why it is
1. The abstraction of arithmetic is a difficult point in primary school teaching. In teaching, we try to transform the abstraction into the concrete by means of visual demonstration, so as to make the arithmetic clear
2. Learn to operate with tools, explore and comprehend. Psychologists believe that thinking begins with action. To enable students to master mathematical knowledge and promote the development of thinking, it is necessary to build a bridge between image thinking and mathematical abstraction, and give full play to the role of learning tools. For example, if the students have difficulty in understanding the "method of making up ten" in addition within 20, we will ask them to come out with sticks to help them learn the calculation method of "making up ten" by playing with sticks
3. Contact with practice to deepen understanding. Using students' existing knowledge and experience to understand new knowledge is the main way to construct teaching knowledge structure. Properly using old knowledge in teaching, assimilating new knowledge through analogy, and realizing positive transfer of knowledge are concive to students' understanding of new knowledge and recognition of new knowledge structure. For example, when teaching the calculation method of decimal addition, we can use the rate relationship of RMB units that students are familiar with to explain the reason that decimal points must be aligned
4. Pay attention to perception and strengthen stimulation. For the parts that are easy to be ignored by students, we should pay attention to strengthen the stimulation intensity (such as emphasis on entering and leaving places, emphasis on the treatment of decimal points, etc.) to attract students' attention, leave students a clear and correct impression, and avoid and rece errors in future calculation
5. According to the characteristics that students are prone to illusion and thinking set, we should consciously differentiate and compare the similar concepts, rules and formulas, so as to promote the accurate differentiation of new and old knowledge
6. Practice in time to consolidate and improve. Carry out targeted exercises, strengthen the key points and difficulties in the calculation process, and strive to consolidate in class
7. Pay attention to feedback and correct in time. Timely feedback, find out the students' mistakes, help students analyze the reasons and correct the mistakes in time< Third, we should deal with the relationship between written and oral arithmetic
oral arithmetic is a kind of calculation method which can only calculate and get the results by thinking and language without any tools. It has the characteristics of fast and flexible
mental arithmetic is an important part of computing power. Oral calculation is the basis of written calculation and estimation. Both written calculation and estimation ability are developed on the basis of accurate and skilled oral calculation ability. Without a certain basis of oral calculation, the cultivation of written calculation and estimation ability becomes the water without source. In addition, mental arithmetic is widely used in daily life, proction and scientific research. Therefore, it is very important to insist on the training of oral arithmetic and listening arithmetic in teaching to improve students' computing ability
(1) oral arithmetic teaching must run through the whole process of primary school mathematics teaching. In the lower grades, basic oral arithmetic such as addition and subtraction within 20, multiplication within the table and division are arranged; The middle grade arranges some oral arithmetic which is the basis of written arithmetic and often used in daily life; In order to cultivate students' ability of using knowledge flexibly and their ability of oral calculation, senior students arrange some questions of using operation law to do oral calculation in exercises. Each teaching reference book puts forward the requirements for the oral arithmetic of this semester in stages. Teachers should make the cultivation of oral arithmetic ability to be implemented, and effectively improve students' oral arithmetic ability
(2) arrange oral calculation reasonably. In compulsory textbooks, the basic oral arithmetic, which is the basis of written arithmetic, is taught before written arithmetic, while some difficult but not the most basic ones are taught after written arithmetic, so as to further improve students' oral arithmetic ability. For example, addition and subtraction within 20 is an important foundation of addition and subtraction, and only oral arithmetic is taught. In addition and subtraction within 100, two digit addition, subtraction of one digit and integral tens, such as 27 + 6, 27 + 30, are the basis of both written and oral arithmetic. Therefore, this part of the content before the written calculation, only teaching oral calculation; It is more difficult for students to master double-digit plus or minus double-digit, so the first grade first teaches written arithmetic, and the second grade further requires oral arithmetic. In this way, students can not only learn written arithmetic, but also form a strong ability of oral arithmetic
(3) pay attention to the teaching of oral arithmetic. Oral examples should pay attention to the intuitive demonstration and operation to make students understand the calculation theory
(4) teach students oral arithmetic and develop their thinking. In order to improve students' ability of oral arithmetic, we should teach students correct methods of oral arithmetic. The methods are various, and we should guide students to choose the methods that they can easily understand and master. Never guide students to do oral arithmetic with the method of written arithmetic. Two digit addition: 28 + 37. I find that some students think like this: 8 + 7 = 15, indivial digit is 5, ten digit is 2 + 3 + 1 = 6, ten digit is 6. This is completely the idea of written calculation. In fact, you should think like this: 28 + 30 = 58, 58 + 7 = 75. You don't need to have a vertical pattern in your head
practice has proved that strengthening the training of oral arithmetic can not only improve the calculation level of students, but also develop their thinking ability< Fourth, encourage students to use simple algorithms to improve their ability and develop their thinking
simple calculation is a practical and effective method to improve students' calculation speed. Simple calculation often uses certain operation laws, such as addition calculation often uses addition exchange law, addition combination law, and multiplication exchange law, multiplication combination law, multiplication distribution law, etc. in multiplication calculation, some calculations are simplified from complex to easy. The study of simple calculation can not only improve the students' calculation speed, rece the calculation errors, but also help the development of students' thinking. Therefore, in the teaching process, teachers should strengthen the teaching of simple methods
in addition, let students remember some common data, which can simplify the calculation process and improve the calculation speed. I remember an ecator said that a person's memory before the age of 13 is the best. He can remember a lot of things at this stage. Although he doesn't know why and how, these things don't affect his memory. The unknown reasons of these knowledge will be solved with the growth of his age and the increase of his knowledge. Therefore, we should pay attention to the development of students' memory, especially before the age of 13. The content of calculation in middle and high grades is extensive, comprehensive and comprehensive. Some common operations are often encountered in real life. These operations have no specific rules of oral arithmetic, and must be solved by strengthening memory training. The main contents of my intensive training are as follows: 1) the square result of each number from 1 to 10 in the natural number; ② A method of oral calculation for the square result of two digit number of 5 on a digit; ③ Some specific calculation results, such as 125 × 8＝1000，25 × 4 = 100, 0.25 =, 0.75 =, 0.125 =, 0.375 =, 0.625 = etc. These special calculation results are frequently used in practice, homework and life. If we master and remember them skillfully, we can transform them into abilities, which play a good role in calculation and proce high efficiency< 5. Pay attention to cultivate the good habit of careful examination and calculation
the teaching of calculation also needs to train students to form the habit of careful examination and examination. Don't just shout "be careful!" to students, To teach methods, strict requirements, form habits, improve the accuracy of calculation
the new curriculum standard points out that we should pay attention to the cultivation of students' habit of inspection. Inspection is a good way, it can make people find their own mistakes in time and correct them in time. In the process of teaching, teachers should pay attention to strengthen the teaching of checking calculation, let students use different methods to test a problem, master the test method, and skillfully use this method to judge the correctness of the answers to similar problems
six relations between addition, subtraction, multiplication and division are often used in checking. The estimation is often based on the variation of proct and quotient. For example: according to the multiplier & gt; 1, proct & gt; Multiplicand (except 0); Multiplier = 1, proct = multiplicand; If the multiplier is less than 1, the proct is less than the multiplicand (except 0), you can judge which of the following questions is greater than the multiplicand, which is less than the multiplicand, and which is equal to the multiplicand: 8 × 、 nine × 、 one × 2、0.9 × 16、5 × 1、3 × 、 × 1 According to divisor > 1, quotient < divisor (except 0); Divisor = 1, quotient = dividend; If the divisor is less than 1, the quotient is greater than the divisor (except 0), it can be judged without calculation ÷ 14、8 ÷ 1 、21 ÷ 、 ÷ 7、2 ÷ 1、0.45 ÷ Is the quotient greater than the divisor, less than the divisor, or equal to the divisor< Sixth, enrich learning activities, be happy with teaching and learning, and stimulate students' interest
the calculation problem is composed of numbers and abstract operation symbols, which makes students easily feel irritable and tired. Therefore, teachers should
in this paper, I would like to talk about some superficial understanding of this problem< First, we should fully understand the importance of developing computing ability
one of the aims of primary school mathematics teaching is to cultivate students' computational ability, and teachers must have enough understanding. Some teachers don't pay enough attention to the cultivation and improvement of students' computing ability, and they don't let students find the rules and interests of computing. This is a big obstacle to cultivate and improve students' computing ability, which must be removed. Computational ability is a necessary ability for students< Number and calculation are widely used in daily life, work and study. In the real world, from the perspective of mathematics, there are mainly three aspects: number, quantity and shape. However, measurement is inseparable from number and calculation, and the quantification of body size is inseparable from number and calculation. Therefore, number and calculation are the most basic tools for people to understand the objective world and the basic knowledge and skills that every citizen should master< Number and calculation are the basis for students to learn other mathematical knowledge and even other subjects. This part of the knowledge is not good, students can not enter the normal learning< Number and calculation play an important role in cultivating students' thinking ability. Mastering the process of number and calculation is also the process of cultivating students' abstract generalization ability. In this way, students also develop the ability of abstract generalization in the process of learning to master the knowledge of number and calculation
4. The teaching of number and calculation is concive to infiltrating the enlightenment ecation of dialectical materialism. The concept of number is graally formed and developed with the needs of human life and practice. When teachers want to teach the concept of number, the relationship between calculation method and calculation method, they can infiltrate the enlightenment ecation of dialectical materialism
Second, clarify the calculation theory and improve the teaching quality of calculation
in the teaching of calculation, teachers should pay attention to explain the principle of calculation and reveal the law of calculation, so that students can know what it is and why it is
1. The abstraction of arithmetic is a difficult point in primary school teaching. In teaching, we try to transform the abstraction into the concrete by means of visual demonstration, so as to make the arithmetic clear
2. Learn to operate with tools, explore and comprehend. Psychologists believe that thinking begins with action. To enable students to master mathematical knowledge and promote the development of thinking, it is necessary to build a bridge between image thinking and mathematical abstraction, and give full play to the role of learning tools. For example, if the students have difficulty in understanding the "method of making up ten" in addition within 20, we will ask them to come out with sticks to help them learn the calculation method of "making up ten" by playing with sticks
3. Contact with practice to deepen understanding. Using students' existing knowledge and experience to understand new knowledge is the main way to construct teaching knowledge structure. Properly using old knowledge in teaching, assimilating new knowledge through analogy, and realizing positive transfer of knowledge are concive to students' understanding of new knowledge and recognition of new knowledge structure. For example, when teaching the calculation method of decimal addition, we can use the rate relationship of RMB units that students are familiar with to explain the reason that decimal points must be aligned
4. Pay attention to perception and strengthen stimulation. For the parts that are easy to be ignored by students, we should pay attention to strengthen the stimulation intensity (such as emphasis on entering and leaving places, emphasis on the treatment of decimal points, etc.) to attract students' attention, leave students a clear and correct impression, and avoid and rece errors in future calculation
5. According to the characteristics that students are prone to illusion and thinking set, we should consciously differentiate and compare the similar concepts, rules and formulas, so as to promote the accurate differentiation of new and old knowledge
6. Practice in time to consolidate and improve. Carry out targeted exercises, strengthen the key points and difficulties in the calculation process, and strive to consolidate in class
7. Pay attention to feedback and correct in time. Timely feedback, find out the students' mistakes, help students analyze the reasons and correct the mistakes in time< Third, we should deal with the relationship between written and oral arithmetic
oral arithmetic is a kind of calculation method which can only calculate and get the results by thinking and language without any tools. It has the characteristics of fast and flexible
mental arithmetic is an important part of computing power. Oral calculation is the basis of written calculation and estimation. Both written calculation and estimation ability are developed on the basis of accurate and skilled oral calculation ability. Without a certain basis of oral calculation, the cultivation of written calculation and estimation ability becomes the water without source. In addition, mental arithmetic is widely used in daily life, proction and scientific research. Therefore, it is very important to insist on the training of oral arithmetic and listening arithmetic in teaching to improve students' computing ability
(1) oral arithmetic teaching must run through the whole process of primary school mathematics teaching. In the lower grades, basic oral arithmetic such as addition and subtraction within 20, multiplication within the table and division are arranged; The middle grade arranges some oral arithmetic which is the basis of written arithmetic and often used in daily life; In order to cultivate students' ability of using knowledge flexibly and their ability of oral calculation, senior students arrange some questions of using operation law to do oral calculation in exercises. Each teaching reference book puts forward the requirements for the oral arithmetic of this semester in stages. Teachers should make the cultivation of oral arithmetic ability to be implemented, and effectively improve students' oral arithmetic ability
(2) arrange oral calculation reasonably. In compulsory textbooks, the basic oral arithmetic, which is the basis of written arithmetic, is taught before written arithmetic, while some difficult but not the most basic ones are taught after written arithmetic, so as to further improve students' oral arithmetic ability. For example, addition and subtraction within 20 is an important foundation of addition and subtraction, and only oral arithmetic is taught. In addition and subtraction within 100, two digit addition, subtraction of one digit and integral tens, such as 27 + 6, 27 + 30, are the basis of both written and oral arithmetic. Therefore, this part of the content before the written calculation, only teaching oral calculation; It is more difficult for students to master double-digit plus or minus double-digit, so the first grade first teaches written arithmetic, and the second grade further requires oral arithmetic. In this way, students can not only learn written arithmetic, but also form a strong ability of oral arithmetic
(3) pay attention to the teaching of oral arithmetic. Oral examples should pay attention to the intuitive demonstration and operation to make students understand the calculation theory
(4) teach students oral arithmetic and develop their thinking. In order to improve students' ability of oral arithmetic, we should teach students correct methods of oral arithmetic. The methods are various, and we should guide students to choose the methods that they can easily understand and master. Never guide students to do oral arithmetic with the method of written arithmetic. Two digit addition: 28 + 37. I find that some students think like this: 8 + 7 = 15, indivial digit is 5, ten digit is 2 + 3 + 1 = 6, ten digit is 6. This is completely the idea of written calculation. In fact, you should think like this: 28 + 30 = 58, 58 + 7 = 75. You don't need to have a vertical pattern in your head
practice has proved that strengthening the training of oral arithmetic can not only improve the calculation level of students, but also develop their thinking ability< Fourth, encourage students to use simple algorithms to improve their ability and develop their thinking
simple calculation is a practical and effective method to improve students' calculation speed. Simple calculation often uses certain operation laws, such as addition calculation often uses addition exchange law, addition combination law, and multiplication exchange law, multiplication combination law, multiplication distribution law, etc. in multiplication calculation, some calculations are simplified from complex to easy. The study of simple calculation can not only improve the students' calculation speed, rece the calculation errors, but also help the development of students' thinking. Therefore, in the teaching process, teachers should strengthen the teaching of simple methods
in addition, let students remember some common data, which can simplify the calculation process and improve the calculation speed. I remember an ecator said that a person's memory before the age of 13 is the best. He can remember a lot of things at this stage. Although he doesn't know why and how, these things don't affect his memory. The unknown reasons of these knowledge will be solved with the growth of his age and the increase of his knowledge. Therefore, we should pay attention to the development of students' memory, especially before the age of 13. The content of calculation in middle and high grades is extensive, comprehensive and comprehensive. Some common operations are often encountered in real life. These operations have no specific rules of oral arithmetic, and must be solved by strengthening memory training. The main contents of my intensive training are as follows: 1) the square result of each number from 1 to 10 in the natural number; ② A method of oral calculation for the square result of two digit number of 5 on a digit; ③ Some specific calculation results, such as 125 × 8＝1000，25 × 4 = 100, 0.25 =, 0.75 =, 0.125 =, 0.375 =, 0.625 = etc. These special calculation results are frequently used in practice, homework and life. If we master and remember them skillfully, we can transform them into abilities, which play a good role in calculation and proce high efficiency< 5. Pay attention to cultivate the good habit of careful examination and calculation
the teaching of calculation also needs to train students to form the habit of careful examination and examination. Don't just shout "be careful!" to students, To teach methods, strict requirements, form habits, improve the accuracy of calculation
the new curriculum standard points out that we should pay attention to the cultivation of students' habit of inspection. Inspection is a good way, it can make people find their own mistakes in time and correct them in time. In the process of teaching, teachers should pay attention to strengthen the teaching of checking calculation, let students use different methods to test a problem, master the test method, and skillfully use this method to judge the correctness of the answers to similar problems
six relations between addition, subtraction, multiplication and division are often used in checking. The estimation is often based on the variation of proct and quotient. For example: according to the multiplier & gt; 1, proct & gt; Multiplicand (except 0); Multiplier = 1, proct = multiplicand; If the multiplier is less than 1, the proct is less than the multiplicand (except 0), you can judge which of the following questions is greater than the multiplicand, which is less than the multiplicand, and which is equal to the multiplicand: 8 × 、 nine × 、 one × 2、0.9 × 16、5 × 1、3 × 、 × 1 According to divisor > 1, quotient < divisor (except 0); Divisor = 1, quotient = dividend; If the divisor is less than 1, the quotient is greater than the divisor (except 0), it can be judged without calculation ÷ 14、8 ÷ 1 、21 ÷ 、 ÷ 7、2 ÷ 1、0.45 ÷ Is the quotient greater than the divisor, less than the divisor, or equal to the divisor< Sixth, enrich learning activities, be happy with teaching and learning, and stimulate students' interest
the calculation problem is composed of numbers and abstract operation symbols, which makes students easily feel irritable and tired. Therefore, teachers should
8. Yeah, being played crazy, later will play crazy!
9.
's bitcoin is rising crazily just because central banks are constantly letting money out of the water. Once liquidity is tight, the bubble will burst. according to media reports, good news is coming from the bitcoin market again. In the latest trading day, the price of bitcoin has exceeded US $58000, a new high in recent years. At the same time, in the trading day when bitcoin soared, 140000 bitcoin investors burst their positions, accumulating more than US $1.1 billion. The bitcoin market once again suffered a double day of ice and fire. Optimistic investors continue to increase their positions and bet that the price of bitcoin will soar. On the other hand, many investors have lost their money because of shorting bitcoin
10. February 12, 2014 - can bitcoin become a currency?, Just in the past 2013, a virtual currency called bitcoin was on fire. The crazy rise of its price shocked the world and also made the financial regulatory departments of different countries panic. be born...
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