Methods and skills of fast calculation in primary school mathematics
1, head difference 1, tail difference 10 times two digits, that is, the square of its single digits minus the square of the ten digits of the larger factor. For example, "48x52=2500-4=2496.
2. Multiply two digits with 10 at the beginning and end, that is, one digit is added with 1 and then multiplied by another digit, and the product is the hundredth and tenth digits of the product of two digits, and then the product of two digits is taken as the first and tenth digits of the product of two digits. For example, "14x 16=224", where "4x6=24" and 24 are units and tens respectively, and (1+ 1) x 1=2 "and 2 are hundreds, the answer 224 can be obtained. If the product of the multiplication of two digits is less than two digits, you need to add 0 to the ten digits.
3. Use the "estimated average" to calculate quickly. For example, "7 12+694+709+688=?" Observing the formula, the average value is 7. 0, the difference between each number and the average is accumulated to get 12-6+9- 12=3, and finally it is calculated as "700 x 4+3=2803".
4. Finally, we need to memorize some commonly used data, such as multiplication formula table, pi, 1 square number to 20, prime number table within 20 and so on. When children master this knowledge, the most important thing is to do all kinds of quick calculation exercises.
Expanding reading: how to improve primary school mathematics if it is not good
Mathematics is a very vague concept for beginners; Or, in their view, math is just pocket money, so it seems that no matter how well you learn math, it will not affect your normal life. Over time, this course was forgotten and I couldn't learn it well. So we should start with cultivating interest.
First, stimulate students' interest in learning.
"Interest is the best teacher", "Learning without interest is tantamount to slavery; Where there is no interest, there is no wisdom and inspiration. " Enthusiasm can open the door of thinking and develop intelligence and ability. As a teacher, we should be good at stimulating children's interest in learning.
1, with vivid examples, describe boring concepts, make more use of mathematical knowledge, and improve children's interest in learning.
2. Use speculative questions or experimental conclusions as guidance. This can not only stimulate children's interest in learning, but also inspire their thinking.
3. Ask contradictory questions to arouse students' doubts. Students' doubts and thirst for knowledge are also one of the means to stimulate their interest in learning.
4. Arouse curiosity. Students' thirst for new knowledge and understanding of the unknown are the key points to stimulate their interest in learning.
Second, divergent thinking ability.
The development of creative thinking is also particularly important in teaching. Divergent thinking just embodies the characteristics of creative thinking, such as "associating as soon as possible, making as many assumptions as possible, and putting forward various methods to solve problems", thus becoming a main form of creative thinking. In the process of primary school mathematics teaching, we should consciously cultivate students' divergent thinking ability, but also cultivate students' preliminary logical thinking ability.
1, which induces the psychological tendency of being willing to seek differences.
We should affirm and warmly praise the factors that appear from time to time in children's thinking process, so that children can truly experience the value of their achievements in seeking differences. When students want to find different solutions but can't, teachers should carefully guide them to help them succeed, so that students can gradually develop a conscious sense of seeking differences and develop into a stable psychological tendency. When faced with specific problems, they will take the initiative to make "Is there any other solution?" "Give it a try and analyze it from another angle!" Thinking about seeking differences.
2. Induce flexibility.
Flexibility is a remarkable sign of divergent thinking. Flexibility to problems can only be realized after getting rid of the bondage of habitual thinking mode and the restriction of fixed mode. Therefore, after students have mastered the general methods well, we should pay attention to inducing students to leave the original thinking track, think about problems in many ways and think flexibly. When students' thinking is blocked, teachers should be good at scheduling prototypes, helping students to connect with old knowledge and experience in solving problems, making changes such as transformation, hypothesis, transformation and inversion, and generating a variety of problem-solving ideas.
3. Encourage originality.
In the process of analyzing and solving problems, children can creatively put forward new and different ideas and solutions, which is the performance of original thinking. Although the originality of primary school students is at a low level as a whole, it contains great inventions in the future. Teachers should enthusiastically encourage them to think creatively, boldly put forward different opinions and questions and solve problems in a unique way. Only in this way can children's thinking change from seeking difference and divergence to innovation.
4. Various forms of training.
In the process of primary school mathematics teaching guidance, teachers can take various forms of training to cultivate children's agility and flexibility of thinking, thus inducing children's divergent thinking and cultivating children's divergent thinking ability. First, the topic is changeable: expand, shrink, reverse, compare or describe the conditions, problems and plots in the topic in different forms, so that children can understand the quantitative relationship from different angles in various changing situations. Ask many questions in one picture: when guiding children to observe the same thing, they should observe it carefully from different angles and aspects, know things and understand knowledge. Multi-discussion on one topic: provide a certain mathematical situation, schedule students' old knowledge, skills or experience in many aspects, organize discussions, and cause the impact of thinking sparks. Multi-solution to one problem: under the condition that the conditions and problems remain unchanged, let students analyze and think from multiple angles and sides, and explore different methods to solve problems.
Third, learning methods.
With the requirement for the rigor of mathematics knowledge system appropriately lowered in compulsory education textbooks, the "distance" between knowledge structures has been opened, and it has become a textbook system with complementary structure and problem solving. Therefore, children must master and have certain methods of learning mathematics in order to improve and develop their learning ability.
1. Good study habits. Mr. Ye Shengtao said: All good attitudes and methods must become habits. Only when proficiency becomes a habit can a good attitude and method be displayed anytime and anywhere ... and it will last a lifetime. Therefore, it is of great significance to cultivate students' good study habits from an early age. The main training methods are: preview before class to make the class more purposeful and targeted; Be serious in class, follow the teacher's ideas and speak enthusiastically; Review after class, first review the knowledge learned that day, then do homework, and finally sort out the learning content; Inspection and verification can not only cultivate students' responsible attitude, but also enable students to further understand their own thinking activities.
2. Try activities. Theory is based on practice, and it can only be mastered better if you keep trying. For example, after students have mastered the order of integer elementary arithmetic, they can be asked to try to learn "decimal elementary arithmetic", and then the teacher will give a little instruction: the order of integer elementary arithmetic is also applicable to "decimal elementary arithmetic". Children can assimilate new knowledge and construct a new cognitive structure: the order of all decimal elementary arithmetic is: multiply first, then divide, then add and subtract, and what is in brackets should be counted first.
3. Observation activities. The way of training is: "objective things or phenomena" provided by children have orderly characteristics and bright background, and some observation questions should be given. This helps students to clearly observe the goal, let them observe, think, discuss and make observation records, and discover the laws and essence of mathematics.
4. Thinking activities. Only when students have the direction of thinking and have extensive contact and imagination can they capture rich materials, and then get rid of the rough and the fine, discard the false and keep the true, and find a solution to the problem. Cultivating children for such a long time will help them form a way of thinking and improve the quality of thinking.
5. Self-study activities. With the increase of literacy and the improvement of mathematics knowledge, middle and senior children have a certain foundation of self-study, which mainly refers to students' independent self-study activities in the classroom.
A. Focus on reading some teaching contents, such as the process of "thinking", the conclusion in the box, and outline the key words, which will help children understand the key and essence of reading textbooks.
B. Children can try to do the questions and complete them according to what they read.
C. The teacher asked the children to do exercises similar to examples, and let them talk about their own ideas and why they did it, so as to test the self-study effect of the children.
D. The teacher asked some key questions. In the mutual communication between teachers and students, teachers can do some guidance and induction to help systematically understand and master the content of self-study, and also make people with learning difficulties get compensation for learning.
6. Cooperative learning. For some materials with a high degree of "problems" and difficulties in individual learning and absorption, teachers can change the classroom organization form, let students carry out cooperative learning, and promote them to complete psychological transformation and learn knowledge through mutual complement and inspiration.
7. Combination of numbers and shapes. Mathematics is mainly a subject that studies numbers and shapes, and children's thinking characteristics are in the transition stage from image thinking to abstract thinking. Therefore, the combination of numbers and shapes is the favorite and commonly used method for students to learn mathematics.
In fact, it is not difficult to learn primary school mathematics well. The key is whether you want to learn or not. For children themselves, interest is very important; For teachers, we should learn to guide children and seek better teaching methods for students to accept and absorb. In learning activities, on the one hand, students should have enough study time, so teachers should be willing to spend time for students to learn; On the other hand, we should discuss and cooperate with each other, so that we can easily inspire and complement each other and form better learning methods, thus improving children's mathematics level.