Summary of mathematics knowledge points in the fourth grade of primary school 2022
Summary of Mathematics Knowledge in Grade Four 1
Unit 1 Understanding of Large Numbers
1.1010,000 is 100,000,1010,000 is 1 million,101 million is 10 million,1010 million is 100 million.
The forward rate between two adjacent counting units is "ten", which is called decimal counting method.
Special attention: the difference between counting units and numbers.
2. When using numbers to represent numbers, these counting units should be arranged in a certain order, and their positions are called numbers.
3. Number of digits: A number contains several digits, that is, several digits. For example, 652 100 is a six-digit number.
According to our country's counting habit, every four digits are counted from the right.
6. How to pronounce hundreds of millions or more?
(1) Grading first, starting from high reading. Read level 100 million, then level 10,000, and finally level 1.
(2) Billions should be read according to the pronunciation of billions, and then the word "billion" should be added at the end. Ten thousand series should be read according to the reading method of ten thousand series, and then the word "ten thousand" should be added after it.
No matter how many zeros there are at the end of each level, don't read them. Other numbers have a "0" or several "0" in succession, all of which are read only.
7. How to write hundreds of millions or more?
(1) Write from the top, first write 100 million levels, then write 10,000 levels, and finally write one level.
(2) If there is no unit, just write 0 on the number.
8. Compare the sizes of numbers
① For two numbers with different digits, the number with more digits is larger.
(2) Numbers with the same two digits, starting from the most significant digit.
9. Find out the approximate figure
The mantissa after omitting ten thousand digits depends on the number on one thousand digits; The mantissa after omitting 1 100 million bits depends on the number on1100 million bits.
This method of finding the divisor is called "rounding". Whether it is "rounding" or "decimal" depends on whether the number in the most significant digit of the omitted mantissa is less than 5 or equal to or greater than 5. If less than 5, the mantissa will be discarded; If it is equal to or greater than 5, advance to 1 and then discard the mantissa.
10, indicating the number of objects: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, ... are all natural numbers. There is no object, which is represented by 0, and 0 is also a natural number. All natural numbers are integers.
1 1, the smallest natural number is 0, there is no largest natural number, and the number of natural numbers is infinite.
12. The forward speed between every two adjacent counting units is 10. This counting method is called decimal counting method.
13, ON/CE: switch the clear screen key to clear the contents on the display screen.
AC: Clear the key, clear everything.
Summary of fourth grade mathematics knowledge II
Unit 2 hectares and square kilometers
The area of a square with a side length of 100 meters is 1 hectare.
1 ha = 1 10,000 m2
2. The square with a side length of 1 km has an area of 1 km2.
1 km2 = 1000000 m2
1 km2 = 100 hectare
3, from large units to small units, multiplication rate.
From small units to large units, divided by the forward speed.
4. Square kilometers are suitable for areas with extremely large land area (China, provinces, cities, districts, etc.). ) and marine areas. such as
The area of the Hong Kong Special Administrative Region is about1100 (); Square, campus and other slightly larger land area is suitable for hectares. For example, Tiananmen Square covers an area of about 44 (); Playgrounds, classrooms and other small areas are suitable for square meters. For example, the area of a classroom is about 60 ().
5, rectangular area = length x width
Square area = side length × side length
Summary of fourth grade mathematics knowledge 3
Unit 4 Multiply three numbers by two numbers
1, three-digit times two-digit notation
Firstly, multiply the three digits by the two digits, and the last digit of the product is aligned with the single digits of the two digits; Then multiply the three digits by the number on the ten digits of the two digits, and the last digit of the product is aligned with the ten digits of the two digits; Finally, add the products of the two multiplications.
2, the change law of products
One factor is a constant, another factor is multiplied (or divided) by several (except 0), and the product is also multiplied (or divided) by several.
3. The price of each commodity is called the unit price; How much did you buy? A * * * price is called the total price.
Unit price × quantity = total price
Unit price = total price ÷ quantity
Quantity = total price/unit price
4. How long a * * * has traveled is called distance; Distance per hour (or per minute, etc.). ) called speed; Hours (or minutes, etc. ) is called time.
Speed × time = distance
Speed = distance/time
Time = distance/speed
5. Speed units usually include: km/h, m/min, m/s, etc.
Unit 5 Parallelogram and Trapezoid
1. Two straight lines that do not intersect in the same plane are called parallel lines, or they are parallel to each other.
Note: A∑b is pronounced as: A and B are parallel.
2. When two straight lines intersect at right angles, they are said to be perpendicular to each other, one of which is called the perpendicular of the other, and the intersection of these two straight lines is called the vertical foot. Note: a⊥b reads: A is perpendicular to B.
3. The shortest vertical line drawn from a point outside a straight line is called the distance from the point to the straight line.
4. The line segments perpendicular to two parallel lines are equal in length. Or: the distance between two parallel lines is equal everywhere. You can draw a straight line by taking a point (or an outer point) on the straight line as a vertical line.
5. In the same plane, two straight lines parallel (or perpendicular) to the same straight line are also parallel to each other.
6. Draw a vertical line from one point on one side of the parallelogram to the other. The line segment between this point and the vertical foot is called the height of the parallelogram, and the side where the vertical foot is located is called the bottom of the parallelogram.
7. Hold the two opposite corners of the rectangle with both hands and pull them in opposite directions. You can draw the rectangle into a parallelogram with different shapes, but the perimeter remains the same.
8. Characteristics of parallelogram: easy to deform. Such as retractable doors and elevators.
9. Parallelogram and trapezoid have countless heights.
10, isosceles trapezoid is called isosceles trapezoid. Features: Two waists are equal, and two bottom angles are equal.
A trapezoid with a right angle is called a right trapezoid. Features: A waist is the height of a trapezoid.
12. Take any point from the upper bottom of the trapezoid and draw a vertical line to the lower bottom. The line segment between this point and the vertical foot is called the height of the trapezoid.
13. Two identical triangles can be combined into a parallelogram.
Two identical trapezoids can be combined into a parallelogram.
Two identical right-angled trapezoids can be combined into a rectangle or parallelogram.
14, rectangle is a special parallelogram, and square is a special parallelogram. A square is a special rectangle.
15, the sum of three internal angles of a triangle is 180, and the sum of four internal angles of a quadrilateral is 360.
16, quadrilateral summary
Two groups of parallelograms with parallel opposite sides are called parallelograms.
A quadrilateral with only one set of parallel sides is called a trapezoid.
An isosceles trapezoid is called an isosceles trapezoid.
A trapezoid with right angles is called a right trapezoid.
A quadrilateral with four corners at right angles is called a rectangle.
A quadrilateral with four right angles and four equal sides is called a square.
Summary of fourth grade mathematics knowledge 4
Unit 6 divisor is the division of two digits
1, division by zero method: the same number of zeros are removed from the end of dividend and divisor, and the quotient remains unchanged.
2, divisor is the calculation method of two-digit division:
Divide the dividend from the high order, first try to divide the dividend by the first two digits, if it is less than the divisor, then try to divide the first three digits. Write the quotient except the dividend on the dividend. To calculate each quotient, the remainder must be less than the divisor.
3, the change law of quotient:
Dividend and quotient change in the same way.
Divisor and quotient change in opposite directions.
The property that the quotient is invariant: the dividend and divisor are multiplied (or divided) by the same number at the same time (except 0), and the quotient is invariant.
Divider × quotient+remainder = dividend
(Dividend-Remainder) ÷ Quotient = Divider
Unit 7 Bar Chart
1, the characteristics of bar graph: you can visually see the size of various quantities, which is convenient for comparison.
2. When drawing a bar chart, how many bars a grid represents should be determined according to the specific situation.
Summary of fourth grade mathematics knowledge 5
Measurement of the third unit angle
1, line, ray, line segment
Straight line: it can extend to both ends infinitely, and has no end points.
Ray: It can extend infinitely to one end and has only one endpoint.
Line segment: cannot be extended and has two endpoints. A line segment is a part of a straight line.
2. What are the connections and differences between straight lines, rays and line segments?
(1) Lines and rays can extend indefinitely, so the length cannot be measured.
② Line segments can measure the length.
③ A line segment has two endpoints, a straight line has no endpoint, and a ray has only one endpoint.
A figure composed of two rays drawn from a point is called an angle.
4. The measurement unit of angle is "degree", which is represented by the symbol "degree".
Divide the circle into 360 parts, each with an angle of L degrees, and record it as 1.
5. The size of the angle has nothing to do with the length of both sides of the angle. The angle is related to the size of the fork. The bigger the fork, the bigger the angle.
6. The tool for measuring angles is called a protractor.
7. Steps for measuring the angle:
(1) The center of the protractor coincides with the vertex of the angle, and the 0 scale line coincides with one side of the angle.
② The scale on the protractor on the other side of the angle is the degree of this angle.
8. An angle can be regarded as a graph formed by a ray rotating from one position to another around its endpoint.
9. The angle formed by a ray rotating half a circle around its endpoint is called a right angle. 1 boxer = 180.
10, a ray rotates around its endpoint to form an angle called a fillet. 1fillet = 360.
1 fillet =2 right angle =4 right angle 1 right angle = 90.
1 1 An angle less than 90 degrees is called an acute angle, and an angle greater than 90 degrees and less than 180 degrees is called an obtuse angle.
acute angle