Several key issues of ICO blockchain

1. bitcoin is a kind of virtual digital currency proposed by Nakamoto in 2009. It is characterized by no centralized issuing institution and a fixed total of 21 million pieces. It is not a one-time issue and needs to be proced by miners. Due to the decentralized structure, trust needs to rely on cryptography and consensus mechanism technology to achieve
blockchain is a general technology derived from bitcoin. It implements a decentralized database model. Bitcoin can be called blockchain 1.0 because it has no concept of smart contract. The key technologies of blockchain include cryptography encryption and decryption and consensus mechanism. Blockchain is generally used to combine with specific business logic, which needs to rely on smart contract, which provides an execution mode free from human interference
the IPO of ICO originates from the concept of initial public offering (IPO) in the stock market. It is the behavior of blockchain project to issue token for the first time, raise bitcoin and solve Ethereum and other common digital currencies.

2.

Since 2017, the concept of blockchain, which has been popular all over the society and the world, is still heating up, attracting people and social funds; Boost bitcoin, as well as similar network "encrypted digital currency" (such as ether coin, Wright coin, etc.) price rise, created a lot of "overnight rich" myth. The argument that digital currency and blockchain will subvert tradition and profoundly change the world is constantly rising. The start-up and development of blockchain seems to be coming like a roaring sea, but it is more and more concentrated in coin making and speculation, and more and more trapped in the thinking and paradigm of "bitcoin blockchain" of mining and coin making

in the case that bitcoin must be exchanged with fiat money and must join the network trading platform and other auxiliary links in order to play a greater function, the characteristics of bitcoin blockchain such as area center and disintermediation may have serious problems. In the real world, if the transfer of monetary assets is operated through the bitcoin blockchain system, it will actually increase the intermediary link rather than disintermediation. Moreover, because the bitcoin system is highly anonymous and deliberately evades supervision, it is difficult to fully meet the requirements of anti money laundering and anti-terrorism transportation. On the contrary, many new serious problems may arise, Many arguments about bitcoin and blockchain are difficult to hold

those unseen pain points

the so-called labels of bitcoin blockchain, such as "decentralization", "democracy, equality and freedom", can not stand scrutiny; The truth is that if it puts too much emphasis on "decentralization", it will affect efficiency; Bitcoin has not yet become a real currency; The ICO type fund-raising method is not concive to the development of blockchain... But when people enthusiastically pursue blockchain like faith, they can not see these "pain points":

first, bitcoin blockchain is difficult to build a decentralized, democratic and equal society

bitcoin blockchain system envisages the establishment of an equal and democratic world for all participants, but in fact, the core team of coding maintenance and the main forces involved in mining and operation are not so equal and democratic. Due to the influence of computer computing power, the mining and acquisition of bitcoin are not equal as advertised. As a result of competition, the opportunities of mining and acquiring bitcoin are more and more concentrated on a small number of mining pools or nodes with powerful computing power. However, more and more people are involved in mining, consuming resources, but they may not be able to obtain bitcoin. This makes bitcoin more occupied by a few people, and will enhance its voice or influence on the adjustment of network rules

secondly, there are strict conditions for bitcoin blockchain to "de trust" and "de mediate" point-to-point transactions

3. Bitcoin virtual currency was invented by Nakamoto (alias) in 2009
the underlying technology of blockchain bitcoin is actually that it supports the stability of bitcoin in the past eight years. You can understand it as a subversive accounting method or database, and the core is decentralization
ICO, which is essentially blockchain crowdfunding. If an enterprise does ICO, you can understand it as IPO, But the financing is not money, but virtual currency, such as 3000 bitcoins. Of course, you can choose to sell it in any country in exchange for the legal tender of a country

4. The question is not very clear. Go is to have a forward-looking and appropriate ability to calculate in advance, and in line with the chess theory, general kindergarten children, just learned to play chess or low-level players, hope to consider the follow-up changes of three rounds, that is, the possible changes of the next six hands, which has been very powerful for low-level children (children)

hope you are satisfied, thank you!

5. 1、 Basic training

from the psychological characteristics of different ages of primary school students, the basic requirements of oral arithmetic are different. Low and middle grade students mainly add one or two digits. It is better for senior students to take the one digit by two digit mental arithmetic as the basic training. The specific requirement of oral arithmetic is to multiply the number of one digit and the number of ten digits of two digits, and then add the proct of multiplying the number of one digit and the number of one digit of two digits to the three digits, and quickly say the result. In primary school, this training is a sublimation training of abstract thinking of numbers. It is very beneficial to promote the development of thinking and intelligence. This exercise can be arranged in two periods. One is to read in the morning, the other is to arrange a group at the end of homework. Each group is divided as follows: one digit is optional, corresponding to the number of one digit or ten digit in two digits. There are 18 questions in each group. Let the students write the formula first, then write the number directly after several times of oral calculation. In this way, after a period of time (generally 2-3 months), the speed and accuracy of oral calculation will be greatly improved< Second, the main form of the number of senior primary school students has changed from integer to score. In the operation of numbers, the addition of different denominators is the most time-consuming and error prone place for students, and it is also the key and difficult point of teaching and learning. How to overcome this key and difficult point? It is proved that it is correct to put the oral calculation of fraction operation on the addition of fractions with different denominators. Through analysis and inction, there are only three cases of different denominator addition (subtraction) method, and each case has its oral arithmetic law. As long as students master it, the problem will be solved

1. For two fractions, the large number in the denominator is the multiple of the decimal

for example, "1 / 12 + 1 / 3", in this case, oral arithmetic is relatively easy. The method is: the big denominator is the common denominator of two denominators. As long as the small denominator is expanded by multiple, until it is the same as the big number, the denominator is expanded by several times, and the numerator is also expanded by the same multiple, We can add the fractions with the same denominator for oral calculation: 1 / 12 + 1 / 3 = 1 / 12 + 4 / 12 = 5 / 12

2. The denominator of two fractions is coprime. This kind of situation is more difficult in form, and students are also the most headache, but it can be changed from difficult to easy: after it is divided, the common denominator is the proct of two denominators, and the numerator is the sum of the proct of the numerator of each fraction and the other denominator (if it is subtraction, it is the difference of the two procts), such as 2 / 7 + 3 / 13. The oral calculation process is: the common denominator is 7 × 13 = 91, molecule 26 (2 × 13)＋21(7 × 3) = 47, the result is 47 / 91

if the molecules of both fractions are 1, the oral calculation is faster. For example, "1 / 7 + 1 / 9", the denominator is the proct of two denominators (63), and the numerator is the sum of two denominators (16)

3. Two fractions and two denominators are neither coprime numbers nor multiples of decimals. In this case, we usually use the short division method to get the common denominator. In fact, we can also calculate the general score directly in the formula and get the result quickly. The common denominator can be obtained by enlarging the large number in the denominator. The specific method is: to double the large denominator (large number) until it is a multiple of another denominator decimal. For example, 1 / 8 + 3 / 10 expands the large number 10, 2 times, 3 times and 4 times, and compares it with the decimal 8 every time to see if it is a multiple of 8. When it is expanded to 4 times, it is a multiple of 8 (5 times), then the common denominator is 40, and the numerator is expanded by the corresponding multiple and then added (5 + 12 = 17), and the number is 17 / 40

the above three cases are also applicable to the addition and subtraction method with score< Thirdly, the content of memory training is extensive, comprehensive and comprehensive. Some common operations are often encountered in real life. Some of these operations have no specific rules of oral arithmetic and must be solved by strengthening memory training. The main contents are as follows:

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2. The proct of the approximate value of PI 3.14 with one digit and with several common numbers 12, 15, 16 and 25

3. The denominator is the decimal value of the simplest fraction of 2, 4, 5, 8, 10, 16, 20 and 25, that is, the interaction between these fractions and decimals

the results of the above numbers, whether in daily work or in real life, are used very frequently. After mastering and remembering them, they can be transformed into abilities and proce high efficiency in calculation< Four, regular training

1. There are mainly five laws in this aspect: commutative law and associative law of addition; Commutative law, associative law and distributive law of multiplication. Among them, the multiplication distribution law is widely used and has many forms, including positive use and negative use, and the forms of integer, decimal and fraction. In the multiplication of fractions and integers, students often ignore the application of the law of distribution of multiplication, which makes the calculation complicated. Such as 2000 / 16 × 8, using the law of multiplicative distribution, the result is 1001.5, but using the general method of false fraction is time-consuming and easy to make mistakes. In addition, there are subtraction properties and quotient invariant properties< 2. Regular training. It is mainly the oral calculation method (strategy) of the square result of the two digit number of 5

3. Master some special cases. For example, in fractional subtraction, if the numerator is not enough to be subtracted after general division, and the numerator subtracted is usually larger than the numerator subtracted by 1, 2, 3 and other smaller numbers, no matter how big the denominator is, it can be directly calculated orally. For example, the difference between 12 / 7 and 6 / 7 is only 1. The difference between 12 / 7 and 6 / 7 must be 1 less than the denominator. The result is 6 / 7 without calculation. Another example is: 194 / 99-97 / 99, if the difference between the numerator and denominator is 2, the difference between the numerator and denominator is 2, and the result is 97 / 99. When the subtracted molecule is larger than the subtracted molecule by 3, 4, 5 and other smaller numbers, the result can be quickly calculated orally. Another example is the mental calculation of the proct of any two digit number and 1.5, which is two digits plus half of it< 5. Comprehensive training

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2< 3. Comprehensive training of four mixed operation sequences

comprehensive training is concive to the improvement of judgment ability, reaction speed and the consolidation of oral arithmetic

of course, in order to make students master the above situations, teachers should first use them skillfully, so that they can be handy in guiding and improve the effect. At the same time, the training should be carried out persistently. It is difficult to achieve the expected effect to catch fish in three days and dry the net in two days.

6. 1、 Curriculum reform is the core content of the whole ecation reform and one of the key links to promote quality ecation. Mathematics is an important part of the national basic ecation curriculum reform. In today's society, many countries regard mathematics ecation as an important part of citizen quality ecation in the development strategy of basic ecation, and put it in a prominent position. Calculation is the most widely used mathematical method in people's life, study, scientific research and life practice. It is also one of the important tools for people to understand the objective world and the surrounding things. From an abstract point of view, the manifestation of the objective world can be summarized as: number, quantity, space and time, and the relationship between them. From the point of view of mathematics, it is mainly manifested in number, quantity and form. Calculation is inseparable from number and calculation, and the quantification of spatial form and its relationship is inseparable from number and calculation. After the law of any subject is reced to formula, four mixed operations are basically used to calculate. 2、 Research status 1. Teachers do not have a good understanding of the cultivation of students' computational ability. They only pay attention to students' written calculation ability, but ignore students' oral calculation ability and estimation ability. In fact, it is very important to cultivate students' oral calculation ability. In the four calculations, oral calculation is the foundation, and the foundation must be laid well. The accuracy of students' written calculation is in direct proportion to their oral calculation ability. In daily life, there is calculation everywhere, and estimation is indispensable everywhere. With the rapid development of computing tools and the wide use of computers, the content and requirements of large number computing are being adjusted. Therefore, in a sense, the application of estimation has greatly exceeded the accurate calculation. 2. Teachers only pay attention to the results of students' calculation, but do not pay attention to the process. In fact, calculation is a complex operation process, which requires a lot of operation steps to get a result. We should carefully analyze what is wrong. When correcting the calculation questions, we should point out the wrong step according to the students' calculation order. Let the students know the cause of the error and then correct it. 3. Teachers don't pay enough attention to the teaching of calculation. In teaching, they pay more attention to the cultivation of students' logical thinking ability and space concept, but ignore the cultivation of calculation ability. They think that there is a high technology now, and students can use computers and calculators to calculate as long as they can. As a result, there is a deviation in concept, so students should be able to understand the calculation theory and algorithms, By solving practical problems, the computing power is further improved. 4. Students don't re calculate theory, they only focus on algorithm. When they learn to calculate, they don't understand the calculation theory, that is, why they calculate in this way, but they attach great importance to the calculation algorithm, thinking that as long as they can calculate. There is a general lack of interest in calculation problems. They think that calculation problems can be solved without thinking, resulting in cognitive bias, so that they are not serious enough. 5. The students' consciousness of simple calculation is not strong. The students' calculation method is not reasonable and flexible. The students' calculation method should be flexible and diverse. Choose a reasonable algorithm from a variety of solutions to achieve the optimization of the algorithm. In fact, the students' consciousness of simple calculation is not strong. If a calculation problem is not required to be simple, the problem that can be easily calculated will not be easily calculated, We can't choose the best way to solve the problem according to the characteristics of the specific formula. 3、 The definition of the subject calculation teaching mainly refers to the teaching of operation significance and calculation method. The teaching of operation meaning and calculation method is combined. Primary school students' computational ability refers to the students' higher accuracy and appropriate speed in basic mathematical calculation according to the requirements of curriculum standards, including the mastery of basic methods and reasonable and flexible use. This topic focuses on the new curriculum concept under the guidance of mathematics classroom teaching to cultivate students' good calculation habits, promote students to master the calculation method, improve the accuracy of students' mathematical calculation, make it to a certain degree of proficiency, and graally achieve the reasonable and flexible calculation method. 4、 Objective 1. To enable students to understand the basic principles of number operation and to use a variety of methods for calculation; It enables students to explore and understand the law of operation, preliminarily understand the mathematical thought of incomplete inction, preliminarily experience the orderliness of mathematical thinking, and be able to use the law to carry out simple operation, so as to improve their calculation ability from various aspects. 2. Improve the teaching method of calculation teaching, improve the teaching value and efficiency of calculation teaching. 3. Through the research to seek teaching strategies to improve students' computing speed and accuracy, summarize the training methods to improve students' computing ability, so as to improve students' academic performance and lay a solid foundation for students' future study. 4. In the research, we should cultivate teachers' awareness of scientific research and constantly improve teachers' level of ecational research. 5、 Research content around the focus of the research, we will research content is divided into three parts: 1, to promote students to develop good computing habits. Some students have low computing ability, of course, there are some reasons, such as unclear concepts, no real understanding of computing theory, no proficiency in algorithms and so on, but not forming a good habit of computing is also one of the important reasons. Some of them have bad habit of examining questions, and they often do it after half reading; In some cases, the writing is not standardized, the numbers and operational symbols are scribbled, and the numbers and symbols are copied wrongly; Some do not have the habit of checking the calculation and finish the calculation. In view of these phenomena, we believe that in order to improve students' computing ability, we should first cultivate students' good computing habits and let them master some methods. We will study how to promote students' good calculation habits in classroom teaching, extracurricular practice, examination and testing. 2. Using classroom teaching to improve students' computing ability. The basic knowledge of calculation is widely distributed in primary school mathematics textbooks. Every mathematics teacher is required to be familiar with the teaching requirements of each textbook, carefully design teaching plans according to pupils' cognitive rules, age characteristics and knowledge base, and flexibly control the teaching process. At the same time of strengthening the basic knowledge, we should also pay attention to the cultivation of ability and development of intelligence, and strive to achieve the best teaching effect. We will focus on the following three aspects: (1) research on the teaching process and method of computing. Dominated by the traditional teaching concept, many teachers adhere to the principle of "practice makes perfect" and implement the "problem sea tactics" in the teaching of computing, which makes more and more students hate and fear computing. Reading the new curriculum standard carefully, it is not difficult to find that the requirement of calculation mentioned "attach importance to the cultivation of students' innovative consciousness and practical ability". This requires us to actively change our teaching concept, set the teaching goal at the thinking process of computing itself, and set the goal at how to carry out the teaching and learning activities of computing, so that students can actively and happily participate in computing, feel the charm of computing, taste the fun of computing, and improve the ability of computing. Therefore, we will study how to use the teaching process and teaching strategies in the classroom of computing teaching to make students really love and understand computing 2) The research of realizing algorithm diversification“ Encouraging algorithm diversification "is an important concept of the new curriculum standard. The essence of algorithm diversification is to let students learn new knowledge from their existing knowledge and experience, and encourage students to explore solutions through independent thinking. The diversity of algorithms has been paid great attention and actively practiced by the majority of teachers, but the understanding and grasp of it are different. We will study how to grasp the essence of algorithm diversification in mathematics teaching, deal with the relationship between algorithm diversification and algorithm optimization, and pursue the rationality and flexibility of algorithm 3) Strengthen the research on the teaching of oral calculation and estimation. Oral arithmetic, also known as mental arithmetic, is a way of directly calculating the number without the help of calculation tools, mainly relying on thinking and memory According to the new curriculum standard, oral arithmetic is not only the basis of written calculation, estimation and simple calculation, but also an important part of calculation ability. It can be seen that the first step to cultivate students' computational ability is to start with the ability of oral calculation. In the aspect of developing students' number sense, mathematics curriculum standard clearly points out that it can estimate the result of operation and explain the rationality of the result. Estimation is one of the effective ways to develop students' number sense, and it is also an important link to ensure the correct calculation, which is very beneficial to improve students' calculation ability. By estimating before calculation, we can estimate the general results and create conditions for the accuracy of calculation; Estimate after calculation can judge whether there are errors in calculation, find out the causes of errors and correct them in time. In the process of students' daily oral and written calculation, whether it is pre calculation or post calculation estimation, it has a certain value. Therefore, we will study how to strengthen the training of oral calculation and estimation, organize students to practice in a planned way, and improve students' ability of oral calculation and estimation by means of test evaluation and competition activities. 3. The positive role of family ecation in improving students' computing ability. Family ecation is an effective supplement and natural extension of school ecation, which plays an important role in the development of students. Students live in the family, the impact of family environment on children is all-round, but also crucial. Nowadays, parents place high expectations on their children and attach importance to the improvement of their children's abilities in all aspects, especially their children's mathematics learning. While some parents supervise and tutor their children, they also employ tutors for mathematics tutoring. However, now parents pay more attention to the cultivation of children's mathematical thinking ability, let the children participate in the special "Olympiad Mathematics" counseling, do not pay enough attention to the cultivation of children's computing ability, and family ecation does not play its e role in improving students' computing ability. Therefore, we will study how to give full play to the unique function of family ecation, strengthen the connection between family and school, communicate with parents and promote each other, and give full play to the supporting role of family ecation in cultivating students' computing ability. 6、 Research methods 1. Inctive dective method. The problems that conform to one operation method are classified for teaching. The purpose of classification is to help students master the calculation method of these problems, and then use dective method to practice. 2. Literature research method is mainly to carry out the comparative study of data and information from multiple perspectives, to understand and master the research results at home and abroad, to learn from successful practices, to draw lessons, and to provide a theoretical framework and methodology for this research. 3. The first is to investigate the teaching situation, learning situation and the possibility of innovative ecation development, so as to make the research practical and feasible; The second is to investigate and study various factors to improve the computing ability, and study relevant countermeasures, so as to make the research targeted and effective; The third is to investigate the change effect of the relevant quality indicators before and after the experiment, so that the research is well grounded and scientific. 4. The members of the research group use the method of ecational experience summary to summarize their teaching experience. At the same time, through the summary of teaching experience, they learn to use the knowledge of ecational science theory, analyze the collected materials and statistical data, and improve their professional level. 7、 Research stage: the main stage of the research: the first stage: from November 2014 to January 2015, the project preparation stage; Understand the research trends of this subject at home and abroad, investigate and study, establish the experimental ideas of the subject, write the research plan and implementation plan. The second stage: from February 2015 to January 2016, preliminary exploration stage; Set up a research group, carry out the study of researchers, and carry out the preliminary experimental work. The third stage: from February 2016 to June 2016, in-depth development stage; According to the implementation

7. Jingdong has a large share of revenue, and the price is generally higher than that of Taobao tmall. The price of some graphics cards can be as low as two or three thousand, and the quality is the same
the quality of Weigang is OK, and it is a first-line manufacturer with Kingston
MgO is a memory foundry, which can proce its own granules. Some of Kingston Viagra also use MgO's memory granules, but MgO's memory is not recommended to buy. It is used by others. Although the price is cheap, the quality is not high.

8. Hello, the circulation of commemorative coins for the year of the ox has been greatly reced compared with that in previous years. At least from now on, there is an appreciation. The market price of commemorative coins with large circulation in previous years is around the face value, so commemorative coins for the year of the Ox are OK.

9. When will it be available? You can check the notice on the official website. We don't know much about it.