Fourth grade, the first volume of mathematics "approximate" knowledge points
Knowledge points of divisor
1, the characteristics of exact number and approximate number.
The exact number is generally in the unit of "one", and the approximate number is in the unit of "ten thousand" or "one hundred million", and the mantissa is omitted.
2. Use rounding method to keep approximate values.
Look at the next number to be reserved according to the requirements in the question. If this number exceeds 5, proceed to the previous number. If it is less than 5, give it up. Regardless of the last few digits of the mantissa. If it is accurate to 10 thousand digits, only a few thousand can be seen, and if it is accurate to 100 million digits, only tens of millions can be seen. Finally, be sure to write the name of the company.
Typical exercise
fill (up) a vacancy
1, a number consists of seven thousands, three hundreds and five tens, and this number is ().
2. From the right, the hundredth place is (), and the fifth place is ().
3. 3465 digits are () digits, which are () digits. "6" is in the () position, which means (). "3" is in the position of (), which means ().
4. There is () ten in 100, () hundred in 1000, and () one in10.
The four digits of 5 are (), and the three digits of 5 are (). Their sum and difference are (). It consists of () thousand, () hundred and () one.
6. The reading method of numbers within10000 is to read in numerical order from () bit; () How many students are there? () thousands; What are the hundreds of students who participated in ()? There are one or two zeros in the middle, which are read-only () zeros; No matter how many zeros () are at the end.
Second, write down the approximate figures of the following figures.
The divisor of 698 is: the divisor of 2956 is:
The divisor of 3 120 is:
The divisor of 1004 is:
Summary of statistical knowledge points in the first volume of mathematics in the fourth grade of primary school
Planting garlic seedlings (1) (bar chart)
Knowledge points:
1 and 1 in the statistical chart represent different units, so it is necessary to judge how many units 1 represents according to the specific situation. The amount of data is large, and each 1 grid represents more units, while the amount of data is small, and each 1 grid represents fewer units.
2. Understand the meaning of the data on the bar chart.
3. Make clear the characteristics of the bar graph: intuitive, convenient and easy to check.
4. Bar chart making method: determine the horizontal direction and mark the items; Determine the number represented by the vertical direction (the number represented by one grid); Draw straight lines with different lengths according to the size of the data; Write the title.
Supplementary knowledge points: get a preliminary understanding of the composite bar chart, get information from it and answer the corresponding questions.
Planting garlic seedlings (2) (broken line statistical chart)
Knowledge points:
1, broken-line statistical chart: you can get the information of data changes and make simple predictions.
2. The method of broken-line statistical chart: on the grid paper, mark the points according to the given data, and then connect the points with lines in order.
3. Be able to see the information provided by the dotted statistical chart and answer related questions.
Supplementary knowledge points:
1. The difference between a bar chart and a line chart: a bar chart indicates the quantity with a straight line, and a line chart indicates the change of quantity with a broken line.
2. Have a preliminary understanding of the statistical chart of compound broken lines, from which we can get the corresponding information and answer the questions raised.
Learning methods of Olympic mathematics in the fourth grade of primary school
1, grab the classroom. Mathematics study focuses on weekdays and is not suitable for surprise review. The most important thing to study on weekdays is to attend class for 40 minutes. Listen attentively and keep your thoughts close to the teacher. At the same time, it should be pointed out that many students tend to ignore the mathematical ideas and methods taught by teachers and pay attention to the answers to questions. In fact, the way of thinking is far more important than the answers to some questions.
2. Complete the homework with high quality. The so-called high quality refers to high precision and high speed. When writing homework, I sometimes repeat the same type of questions. At this time, we should consciously examine the speed and accuracy, and we can have a deeper thinking about this kind of problem every time we finish it, such as the content it examines, the mathematical thinking method used, the rules and skills of solving problems, etc. In addition, the thinking questions assigned by the teacher should also be carefully completed. If you don't give up easily, you must carry forward the spirit of "nails" and think quietly whenever you have time. Inspiration always pops up in front of you. Most importantly, this is an opportunity to challenge yourself. Success will bring self-confidence, which is very important for learning mathematics; Even if you fail, this question will leave a deep impression on you.
3. Think hard and ask more questions. First of all, for the concepts and laws given by teachers, we should not only know "why", but also know "why" and get to the bottom of it. This is the way to understand. Secondly, we should be skeptical about learning any subject, especially mathematics. If you have any questions about the teacher's explanation and the content of the textbook, please feel free to ask questions and discuss with the teacher. In a word, thinking and asking questions are the ways to eliminate hidden dangers in learning.
4. Summarize and compare, and clear your mind.
(1) summary and comparison of knowledge points. After learning a unit, you should sort out the contents of this chapter or go through it in your mind to clarify the relationship between them. Similar and confusing knowledge points should be summarized and compared separately, and sometimes they can be distinguished by association.
(2) Summary and comparison of topics. Students can set up their own question bank. I have two sets of problem sets. One is wrong and the other is accurate. Write down the mistakes in the usual homework and exams selectively, and mark the matters needing attention with a red pen on one side. Just read what is written in red pen before the exam. I also wrote down some extremely clever or difficult problems I saw, and marked the methods and ideas used in this problem with a red pen. After a long time, I can sum up some types of problem-solving rules and write them down in red notes. In the end, they will become your precious wealth and be of great help to your math study.
5. Do extracurricular exercises seriously. Spare time is very precious to our primary school students, so you should be accurate and precise when you do extracurricular exercises. As long as you do three or two pages carefully every day, your math study will be "a tower of sand" and fruitful.
New Beijing Normal University printing plate fourth grade mathematics first volume knowledge point article;
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