Elementary school fourth grade first volume mathematics knowledge point handwritten report
The following were some of the content suitable for the fourth grade's first volume of mathematics knowledge:
* * I. Number and Counting **
1. * * Counting Unit **
- One, ten, one hundred, ten thousand, one hundred thousand, one million, ten million, hundred million, one billion…They were all units of measurement. The progression rate between every two adjacent counting units was 10. This counting method was called the decimal counting method.
- Ten thousand is ten thousand, ten ten thousand is one hundred thousand, ten hundred thousand is one million, ten one million is ten million, ten million is one hundred million, ten one hundred million is one billion, ten billion is ten billion, ten ten billion is ten billion.
2. * * Reading and Writing **
- When reading, start from the high position, first read 100 million, then read 10,000, and finally read 1. The 0 at the end of each level was not read, and the other digits had one 0 or several 0s, so only one "zero" was read.
- When writing numbers, the numbers above the ten thousand level and the hundred million level were written according to the method of counting on the level. If there was not enough, 0 would be used to make up for it.
* * 2. Unit Conversion **
1. * * Conversion of length units **
- 1 meter = 10 decimeters, 1 decimeter = 10 centimeters, 1 centimeter = 10 millimeters, 1 kilometer = 1000 meters, 1 decimeter = 100 centimeters, 1 meter = 100 centimeters.
2. * * Area Unit Conversion **
- 1 square meter = 10000 square centimeters, 1 hectares = 1000 square meters, 1 square meter = 100 square decimeters, 1 square decimeter = 100 square centimeters, 1 square kilometer = 100000 square meters = 100 hectares.
* * Three, the classification of horns **
- Sharp angle: greater than 0 °, less than 90 °; Right angle: 90 °; Obtuse angle: greater than 90 °, less than 180 °; Straight angle: 180 °; Zhou angle: 360 °. And 1 circle angle = 2 straight angles = 4 right angles, the relationship between the size of the angle is acute angle
Elementary school first grade handwritten report second volume mathematics
There were many ways to make and content choices for the second volume of the first-grade mathematics handwritten report. In terms of content, it could include the sorting of mathematical knowledge, such as the abdication of numbers within 20 (this was the knowledge content in the first four units of the second volume of the Beijing Normal University edition), or the understanding of numbers within 100. It could also show the methods of mathematics learning, such as the method of orderly thinking. At the same time, he could incorporate famous mathematicians 'sayings. For example, the famous mathematician Gauss once said,"Mathematics is the science of the universe. It can appear by your side at any time." In terms of aesthetics, colored lead could be used to draw illustrations and color the content section. If he chose colored lead, the erasable-colored lead was a good choice. It had a high color saturation, and it was smooth and difficult to break the lead. Moreover, if he made a mistake, he could easily erase it with an ordinary eraser. It could not only ensure the color of the handwritten report, but also make it easy to modify. The overall layout of the handwritten newspaper had to be cleverly conceived. With bright colors, through hands-on, brain-on, and painting, the handwritten newspaper with distinct personalities was created. The art foundation and knowledge were integrated into one, fully demonstrating the creativity of the students. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Elementary school fourth grade mathematics first volume knowledge point collection
The following is a collection of knowledge points in the first volume of fourth grade mathematics: 1. ** Conversion of length units **: 1 meter = 10 decimeters, 1 decimeter = 10 centimeters, 1 centimeter = 10 millimeters, 1 kilometer = 1000 meters, 1 decimeter = 100 centimeters, 1 meter = 100 centimeters. 2. ** Area unit conversion **: 1 square meter = 10000 square centimeters, 1 hectares = 1000 square meters, 1 square meter = 100 square decimeters, 1 square decimeter = 100 square centimeters, 1 square kilometer = 100000 square meters = 100 hectares. 3. ** The classification of angles **: acute angle (greater than 0° but less than 90°), right angle (90°), obtuse angle (greater than 90° but less than 180°), flat angle (180°), and peripheral angle (360°). 1 peripheral angle = 2 flat angles = 4 right angles. The relationship between the sizes is acute angle <right angle <obtuse angle <flat angle <peripheral angle. 4. ** Four operations related **: Multiplying 0 by any number will result in 0; dividing 0 by any number that is not 0 will result in 0. 5. ** Formula related to economic problems **: Unit price × quantity = total price, total price/unit price = quantity, total price/quantity = unit price. 6. ** Formula for the itinerary problem **: Distance/time = speed, distance/speed = time, speed × time = distance. 7. ** Rectangle and square area formula **: Rectangle area = length x width (length = area/width), square area = side length x side length. 8. The smallest composite number is 4, the smallest prime number is 2, the smallest even number is 0, the smallest odd number is 1, the smallest factor is 1, the smallest single-digit number is 1, the smallest natural number is 0, and the largest unit of fraction is 1/2. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Elementary school fourth grade making simple model mathematics handwritten report
The following are some steps and content suggestions for making a fourth-grade simple model mathematics handwritten report: ** I. Hand-copied overall planning ** 1. ** Title * - Use eye-catching font to write titles such as "The Wonder of Mathematical Models" or "Entering the World of Mathematical Models." 2. ** Sectors ** - It could be divided into three to four sections, and they could be distinguished by colored pens or lines of different colors. ** 2. Fill in the content ** 1. ** Mathematical Model Introduction Section ** - A mathematical model is a mathematical structure that uses mathematical language to describe the characteristics, quantitative relationships, and spatial forms of things in the real world. For fourth-year students, there were some simple examples, such as using a rectangular representation of the area model of the playground. The length multiplied by the width could get the area of the playground. - He could write some common mathematical models, such as geometric models (such as simple graphic models such as triangle and square, used to calculate perimeter and area) and quantity relationship models (such as unit price x quantity = total price). 2. ** Simple Model Creation Section ** - Choose a simple mathematical model to explain the production process in detail. For example, the content of the mathematical manuscript for making a cube model: - [Material preparation: You can use paper or small wooden sticks.] If paper was used, prepare six square pieces of paper of the same size. - "Production steps: First, fold the sides of the square paper in half. Then, paste or fold the six pieces of paper according to the connection method of the cube's surface to obtain a cube model. Moreover, he could draw a simple cube expansion diagram beside it and mark the position relationship of each surface. - He could also introduce the method of making a cuboid model, such as first determining the length, width, and height of the cuboid, then cutting out the surface of the cuboid according to the corresponding size, and then combining and sticking it. 3. ** Model and Life Section ** - Illustrate the application of mathematical models in life. For example, when construction workers built houses, they would use the concept of cuboids to calculate the size of the room, and when merchants calculated the profit of goods, they would use the profit model (profit = selling price-cost). - It was accompanied by some simple illustrations of life scenes, such as houses, shops, etc., to directly show the existence of mathematical models in life. 4. ** Interesting mathematical model story section (option)** - It was a short story related to mathematical models. For example, when the ancient Greek mathematician, Archmedes, studied the volume of an object, he put an irregular object into water and used the water displacement volume model to calculate the volume of the object. ** 3. Handwritten copy decoration ** 1. Use colored lead (like the previously mentioned, the color is saturated and not easy to make mistakes) to draw some mathematical elements, such as numbers, simple geometric figures (triangle, circle, etc.) as borders or embellishments. 2. Draw some small pictures related to the mathematical model in the blank space. For example, draw a few cubes of different colors in the introduction of the cube model. 3. Pay attention to the color matching. The overall style should be simple and clear, in line with the aesthetic standards of fourth-year students. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Elementary school student grade 5 mathematics score handwritten report
The following is a hand-written report for fifth-year math scores: * * I. Basic Concepts of Scores ** 1. * * The definition of scores ** - A score represents a fraction of another number, or the ratio of one event to all events. Divide the unit "1" into several parts, and the number that represents such a part or several parts is called a score. For example, if a cake was divided into eight equal portions, three of them could be represented by a score of 3/8. 2. * * The composition of scores ** - A score was made up of a numerator, a numerator, and a line. The number above the score line was the numerator, which represented the number of shares taken, and the number below the score line was the Denominator, which represented the number of shares divided equally by the unit "1". For example, in a score of 5/6, 5 is the numerator and 6 is the numerator. * * 2. The nature of the score is related ** 1. * * The Basic Nature of Scores ** - If the numerator and numerator of a fraction are multiplied or divided by the same number (except for 0), the size of the fraction remains unchanged. For example, 1/2 = 2/4 = 4/8, the numerator and numerator of 1/2 multiplied by 2 to get 2/4, and multiplied by 4 to get 4/8. 2. * * Approximately Points ** - To convert a fraction into a fraction that is equal to it but has a smaller numerator and numerator is called a reduction. For example, 12/18, the greatest common factor of 12 and 18 is 6, and the numerator and numerator are divided by 6 to get 2/3. 2/3 is the simplest fraction after 12/18 is reduced. 3. * * General score ** - The general fraction is to convert a few scores with different predictors into a fraction with the same predictors that is equal to the original fraction. For example, comparing the size of 2/3 and 3/4 required a general fraction. The least common multiple of 3 and 4 was 12, 2/3 = 8/12, and 3/4 = 9/12. This way, the size could be compared. * * 3. Calculating the fraction ** 1. * * Adding and Subtracting ** - If you add and subtract the same fraction, the numerator will add and subtract. For example, 3/8 + 2/8 =(3 + 2)/8 = 5/8. When adding and deducting the scores with different predictors, the general fraction would be used first, and then the calculation would be done according to the rules of addition and substitution of the scores with the same predictors. For example, 1/2 + 1/3 would be 3/6 + 2/6 =(3 + 2)/6 = 5/6. 2. * * Multiplication ** - Multiplying a fraction by an entire number, the numerator was the product of the numerator of the fraction multiplied by the entire number, and the numerator remained unchanged. For example, 2/3 × 3 =(2 × 3)/3 = 2; multiply a fraction by a fraction, using the product of the numerator multiplied by the numerator as the numerator, and the product of the numerator multiplied by the numerator multiplied by the numerator as the numerator. For example, 2/3 × 3/4 =(2 × 3)/(3 × 4)= 1/2. 3. * * Division ** - Dividing a number by a fraction is equal to the inverse of the number multiplied by the fraction. For example, 2 × 1/3 = 2 × 3 = 6. * * 4. The application of scores in life ** 1. * * Item splitting problem ** - In life, we often encounter situations where things are divided. For example, if 10 apples were evenly distributed to 5 children, the number of apples each child received would be 10/5 = 2. It could also be expressed as 10/5 = 2/1 apples per child. 2. * * Proportional problem ** - If the ratio of fruit juice to water was 1:3, then the fruit juice accounted for 1/(1 + 3)= 1/4 of the total amount of the beverage, and the water accounted for 3/(1 + 3)= 3/4 of the total amount of the beverage. * * 5. Interesting Mathematics ** 1. * * History of Scores ** - The ancient Egyptians were the first to use scores, but their method of expressing scores was rather strange. They only used a fraction with a numerator of 1. For example, 2/3 was represented by 1/2 + 1/6. 2. * * Score Puzzle ** - For example, if the numerator is 3 smaller than the numerator, and the sum of the numerator and the numerator is 13, what is the score? (The answer is 5/8) In terms of the design of the handwritten paper, different colors of colored lead could be used to draw some patterns related to the score, such as dividing a circle into several parts to represent the score, or drawing some small illustrations of cake and fruit. At the same time, attention should be paid to the neatness of the font and the rationality of the typography, so that the handwritten newspaper was beautiful and could accurately convey mathematical knowledge. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Elementary school sixth grade first volume mathematics knowledge point three
The following is a summary of the sixth grade mathematics knowledge points: ** 1. Concepts related to numbers ** 1. ** Intents ** - The concept of positive and negative numbers needed to be grasped. It was clear that positive numbers were numbers greater than 0, and negative numbers were numbers less than 0. - The rules of addition and substitution of the whole numbers included the addition and substitution of the same symbols, as well as the addition and substitution of different symbols. - For the multiplication and division operations of an integral number, one had to understand that multiplication was a simple operation of the same addend, while division was the inverse operation of multiplication. At the same time, one had to pay attention to the symbol rules in the operation. 2. ** Points ** - The concept and basic nature of scores. Scores represented the division of a whole into several parts, one or several parts. The basic property of a fraction was that the numerator and the numerator were multiplied or divided by the same number (except for 0), and the size of the fraction remained unchanged. - To add and subtract a fraction, one had to add and subtract a fraction with the same Denominator. If the Denominator did not change, the Numerator would be added and deducted. If one added and deducted a fraction with a different Denominator, one had to first divide it into a fraction with the same Denominator before calculating. - The multiplication and division of scores. Multiplying a fraction by an integral was a simple operation to find the sum of several identical scores. The numerator and the integral were multiplied, and the numerator remained unchanged. Multiplying a fraction by a fraction was to use the product of the numerator as the numerator, and the product of the numerator as the numerator. Fraction division was the inverse of fraction multiplication. Dividing by a fraction was equal to multiplying by its inverse. - The relationship between a fraction and an entire number was that an entire number could be regarded as a fraction with 1 as the Denominator. 3. ** Decimals ** - The concept and representation of decimals. The decimals were a special representation of real numbers, consisting of an integral part, a decimals part, and a decimals point. - To add and subtract decimals, one had to calculate them in line with the decimal point. - For multiplication and division of decimals, the multiplication of decimals was calculated according to the rule of multiplication of whole numbers. Then, the number of decimals in the factor was counted from the right side of the product, and the decimals were marked. For division of decimals, when the division was an integral number, it was calculated according to the rule of division of whole numbers. The decimals of the quotient should be aligned with the decimals of the dividends. When the division was a decimals, the division should be converted into an integral number before calculation. - The relationship between decimals and scores was that decimals could be converted into scores, and scores could also be converted into decimals. 4. ** Multiple and Subordinate of Numbers ** - The concept of multiple and common multiple was that if one whole number could be divided by another whole number, the whole number would be a multiple of the other whole number. The common multiple referred to two or more natural numbers, and if they had the same multiple, the multiple would be their common multiple. - Divisors are also known as factors. If the quotient of an integral a divided by an integral b(b = 0) is an integral without a remainder, we say that b is a quotient of a. A common quotient refers to an integral that can be divided by several integral numbers at the same time. - The greatest common factor and the least common multiple. The greatest common factor referred to the largest common factor of several numbers, and the least common multiple referred to the smallest common multiple of several numbers except for 0. ** 2. Fraction multiplication ** 1. ** Meaning of fraction multiplication ** - The meaning of multiplying an integral by a fraction was the same as multiplying an integral. It was a simple operation to find the sum of several identical addenda. The second factor must be an integral. - The meaning of multiplying a number by a fraction was to find the fraction of a number. The second factor must be the fraction. 2. ** Multiplication Method for Fraction ** - The algorithm for multiplying a fraction by an integral was to multiply the numerator by the integral, with the numerator unchanged. If it was possible to reduce the fraction, then calculate it. - The algorithm for multiplying a fraction by a fraction was to use the product of the numerator multiplied by the numerator as the numerator and the product of the numerator multiplied by the numerator as the numerator. If the formula contained a fraction, the fraction had to be converted into a fake fraction before the calculation. 3. ** Relationship between product and factor ** - A number (except 0) multiplied by a number greater than 1, the product is greater than this number. - A number (except 0) multiplied by a number less than 1, the product is less than this number. - A number (excluding 0) multiplied by 1, the product is equal to this number. 4. ** Mixed fraction and multiplication ** - The order of the mixed operations of fraction multiplication was the same as that of the whole numbers. Multiply first, divide first, then add and subtract. If there were any parenthesis, then calculate the ones inside the parenthesis first, and then calculate the ones outside the parenthesis. ** 3. Knowledge Points related to application questions ** 1. ** Itinerary problem ** - To understand the relationship between speed, time, and distance, distance = speed x time. When solving the travel problem, he could flexibly use this formula to solve the unknown quantity according to the known conditions. 2. ** Diagram Area Calculation ** - For simple shapes such as rectangular, square, triangular, quadrilateral, and echelon, you must remember the area calculation formula. - For complex combination graphs, they could be cleverly divided and reorganized into simple graphs that had been learned, and then the corresponding geometric formulas could be used to solve the area. In this process, one must pay attention to the observation and thinking of the characteristics and laws of the graph, and cultivate the ability of spatial imagination and logical thinking. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Elementary school fourth grade essay handwritten edition volume 2
The second volume of the handwritten version of the fourth-grade elementary school essay might involve the content of the unit synchronization essay. There were different unit topics in the fourth grade's second volume of the essay. For example, the second unit," My Wonderful Thoughts," could be written with a comparison, suspense, future, parallel, and explanation. Another example was Unit 6," I've Learned___", which had some writing points. Firstly, the selection of materials had to be outstanding. Considering the difficulty, steps, uniqueness, and other factors, the topic had to be as detailed as possible. Secondly, he could write down two or three failures in the middle, and write down the failure process in detail. Third, every step had to have an action and a result, and the thoughts in his heart after the result was produced. In addition, there were some essays that involved describing specific scenes such as one's own paradise, and there were corresponding model essays for reference. These contents could help students learn the fourth grade essay writing by organizing handwritten notes. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Elementary school fourth-grade mathematics commonly used formulas, volume 2
1. ** Perimeter Formula **: C = 2 pi r (used to calculate the circumference of a circle). 2. ** Area formula **: S = Pi r2 (Find the area of a circle with a known radius); Rectangle area = length x width; Square area = side length x side length. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Elementary school fourth-grade mathematics hand-copied report operation law
The following are some suggestions for the content of the fourth-grade mathematical operation law manuscript: ** The first and fourth operation order section ** 1. ** Parenthesis-less formula ** - In an equation without parenthesis, when it came to addition, multiplication, and division, the order of operation was to calculate multiplication and division first, then addition and addition. For example, to calculate $96 div12 + 4×2$, one would first divide $96 div12 = 8$and multiply $4×2 = 8$, then add $8+8 = 16$. 2. ** Parenthesized formula ** - ** Parentheses **: The order of mixed operations with parenthesis is to calculate the ones inside the parenthesis first, then the ones outside the parenthesis. For example,$96 × (12 + 4)×2$, add $12 + 4=16$, then divide $96 × 16 = 6$, and finally multiply $6×2 = 12$. - ** Square Parentheses **: The order of mixed operations with square parenthesis is to first calculate the ones inside the small parenthesis, then calculate the ones inside the square parenthesis, and finally calculate the ones outside the square parenthesis. For example,$96 × [(12 + 4)×2]$, the addition in the small parenthesis was $16$, then the multiplication in the square parenthesis was $16×2 = 32$, and finally the division was $96 × 32 = 3$. As the number of steps increased, it was possible to use curly brace. The order of operation was small brace first, then middle brace, and finally curly brace. ** 2. The addition operation rule section ** 1. ** Commutative law of addition ** - It was defined as two addenda exchanging positions, and the sum did not change. It was expressed in letters as $a + b=b + a$. For example,$348+76 = 76+348$. 2. ** Association of addition ** - The definition was to add the first two numbers, or add the last two numbers, and the sum would not change. The letters are represented as $(a + b)+c=a+(b + c)$. For example,$(235 + 456)+44$, you can first calculate $456 + 44 = 500$, and then add $235$, which is $456+44+235$, or you can write $235+(456 + 44)$. For $168 + 48+32 + 52$, you can use the law of addition to make up a hundred. First, calculate $168+32 = 200$and $48 + 52 = 100$, and then add the sum of the two numbers, which is $(168+32)+(48 + 52)$. ** 3. Subtraction section ** 1. ** Subtraction operation property 1 ** - If a number was continuously reduced by two numbers, then the positions of the latter two deductions could be swapped. The letters are represented as $a-b- c= a-c- b$. For example,$786 - 78 - 86 = 786 - 86 - 78$. 2. ** Subtraction operation property 2 ** - If two numbers were deducted from a number, it was equivalent to deducting the sum of the two numbers from the number. The letters are represented as $a - b - c=a-(b + c)$. For example,$896 - 64 - 36 = 896-(64 + 36)$. ** 4. Multiplication Rule Section ** 1. ** Commutative law of multiplication ** - The positions of the two factors were swapped, and the product remained unchanged. It is expressed in letters as $a×b = b×a$. For example,$53×42 = 42×53$. 2. ** Combination of multiplication ** - Multiply the first two numbers, or multiply the last two numbers, the product remains the same. The letters are expressed as $(a×b)×c=a×(b×c)$. For example,$56×5×2$could be calculated as $5×2 = 10$, then multiplied by $56$, which was $5×2×56$or $56×(5×2)$. For $125×4×25×8$, using the law of multiplication, first calculate $125×8 = 1000$and $25×4 = 100$, and then multiply the two products, that is,$(125×8)×(25×4)=100000$. 3. ** Multiplication distribution law ** - When the sum (minus) of two numbers was multiplied by a number, they could be multiplied by the number and then added (minus). For example, if you calculate $4752×286 - 4753×285$, turn $4752$into $4753 - 1$, and then calculate it according to the distribution law. He could also add some relevant practice questions or interesting mathematical knowledge to enrich the content. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Elementary school mathematics fourth grade second volume class lesson plan
The following is part of the teaching plan for the fourth grade of primary school mathematics: - In terms of the four operations, it included the meaning of multiplication and division and the relationship between the various parts of the lesson plan. It would involve students understanding the meaning of the four arithmetic operations, grasping the relationship between each part of the four arithmetic operations, exploring and understanding the operation laws of addition and multiplication, and applying these laws to simple operations. - The significance and nature of decimals, as well as the addition and substitution of decimals, were also important. In the teaching, the students should understand the meaning of decimals, grasp the law of the change of the size of decimals caused by the movement of the decimal point, and carry out the addition and deduction of decimals. - There were also teaching materials related to operational laws and simple calculations. - In the triangle section, it would involve understanding the characteristics of the triangle, classification according to the characteristics of the triangle angle, and understanding the sum of any two sides of the triangle is greater than the third side and the inner angle of the triangle is 180°. - In terms of observing objects, students should be able to identify the shapes of objects or geometric objects seen from different directions. The movement of the figures included the contents of the lesson plan to complete an axis-symmetrical figure on the square paper and move the simple figure horizontally or vertically. - In the section on the average and bar chart, there would be lesson plans to let students understand the meaning of the average, find the average of simple data (the result was an integral number), recognize different forms of bar charts, and perform simple data analysis. - Mathematics and comprehensive application activities were also included in the teaching content. It focused on letting students experience the variety of problem solving strategies, using mathematical ideas to solve problems, and experiencing the process of discovering, proposing, analyzing, and solving problems from reality. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Elementary school fourth grade second volume mathematics addition and substitution calculation
In the second volume of the fourth grade mathematics addition and substitution calculation, there were some important contents: ** 1. Laws of Operations ** 1. ** Nature of Subtraction ** - Subtracting several numbers from a number in a row was equal to the sum of this number minus these deductions. It was expressed in letters as a - b - c=a-(b + c). For example, when calculating [5.17-1.8 - 3.2], the formula could be converted to [5.17-(1.8 + 3.2)=5.17 - 5 = 0.17]. - In the reverse calculation, a-(b + c)=a - b - c). During this process, one must pay attention to the change of symbols. Many students tend to forget to change symbols during the reverse calculation. - There was also the commutative law of substitution, which was expressed as a (a-b- c= a-c- b). 2. ** Moving with Symbols in Same-Level Operations ** - When there was only addition and substitution in the equation (which belonged to the same level of operation), it could be moved with a sign. For example, when calculating the addition and deduction of an equation, such as <79+187 - 187+21>, you can move <187>> to the front, with the minus sign in front of it,<79>> to the back, with the plus sign in front of it, it becomes <79 - 187+187+21>, which makes it easier to calculate. It was also applicable to the addition and reduction of decimals. For example,"5.82+0.18 - 3.6" could be moved to the back of "5.82" with the plus sign in front, and "3.6" could be moved to the back with the minus sign in front, becoming "5.82+0.18 - 3.6=(5.82 + 0.18)-3.6 = 6 - 3.6 = 2.4". 3. ** Rules for Removing and Adding Brackets ** - When removing or adding parenthesis, if there was a "+" in front of the parenthesis, there was no need to change the sign; if there was a "-" in front of the parenthesis, the sign had to be changed."+" became "-","-" became "+". For example,<9.64-(3.64 + 3)>, after removing the parenthesis, becomes <9.64 - 3.64 - 3=6 - 3 = 3>. ** 2. Error-prone Points in Calculation ** 1. Be careful not to be careless when calculating. Be careful not to count addition as deduction or deduction as addition. 2. Remember to add one when carrying out addition, and remember to abdicate and subtract one when abdicating. ** 3. Calculation of decimals ** 1. He had to pay attention to the alignment of the decimals, and then he had to do the calculation according to the method of addition and substitution of the whole numbers. For example,(20.67-1.48 = 19.19\)，\(18.88 - 16.03=2.85\)，\(15.35 - 9.05 = 6.3),(3.26+20.2 = 23.46),(4.23+1.45 = 5.68),(20.85 - 13.3 = 7.55),(4.21+12.74 = 16.95),(18.62 - 17.01 = 1.61), and so on. 2. The simple operations of decimals were also applicable to the above operational laws, such as the nature of the substitution, moving with symbols, and so on. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>