Elementary school students improve the method of simple arithmetic

How can we improve students' ability to do simple numeracy?

1. Grasp the calculation and cultivate students' agility of thinking.

Accurate and rapid problem-solving thinking activities are an important manifestation of mental agility. The basic training of grasping oral arithmetic can improve students' ability to apply the law. There are two points that should be paid attention to when doing oral arithmetic:

First, if you don't use your pen, using your pen to calculate is not conducive to improving your oral arithmetic ability and cultivating students' agility in thinking. Second, there should be a requirement for speed when calculating, so that students have a sense of urgency.

Second, grasp the neatness and cultivate the flexibility of students' thinking.

The flexibility of thinking reflects the degree of flexibility of thinking activities in terms of choosing angles, application methods, and processes. Mainly focus on the following aspects: (1) Make. It's just a whole number.

10. Whole hundreds, etc., and then calculate. That is, use the rounding method, add more and subtract or subtract more and add more. (2) points.

It is to separate one number in the operation and operate with another number separately to facilitate rounding operations. (3) Estimate. Estimation can improve students' self-examination ability, improve the accuracy of quick calculation, and help cultivate students' flexibility in thinking.

Estimation, in general, estimates certain numbers as the nearest whole to them.

10. Whole hundred, etc., first estimate what the result is about, and then answer accurately. Secondly, it is tested by estimation.

3. Frequent induction to cultivate the profundity of students' thinking.

It mainly refers to the degree of abstraction and logic of thinking activities. Mainly focus on the following aspects of training. (1) Together.

According to the characteristics of rounding, two or more numbers are combined to facilitate oral arithmetic and mental arithmetic. (2) Turn. Transform the arithmetic method, simplify the complex, and promote mental arithmetic.

Guide students to summarize the rules and deepen their understanding and memory of knowledge. (3) Change. It is to change the order of operations, and the variant does not change the value.

According to the definition of the law, change the operation symbols and data to promote the integration of knowledge in students. The first is to grasp the inverse operation, and the second is to grasp the special properties and deepen the deep understanding of the topic, so as to cultivate the profundity of students' thinking and improve their ability to calculate.

Simple calculations are those algorithms:

The commutative law of addition, the law of associative addition, the commutative law of multiplication, the distributive law of multiplication, the nature of subtraction, the nature of division.

First of all, memorize and understand these algorithms.

The second is to do more questions.

The first type: make up the ten methods.

The method of making up ten, as the name suggests, is actually to make up enough ten first, and then add fraction when adding up. For example, 78+9, when using quick calculation, you can split 9 to make up ten, that is, for the convenience of addition, split 9 into 2 and 7, in this way, 2 and 78 are added together, and the whole number 80 is made, plus the remaining 7, the result is 87!

Another example: 77 + 8, when adding, in order to facilitate the integer number, it is also the first to put the back 8, by splitting the number into 3 and 5, 3 can be added with the previous addition 77, into the whole ten number 80, plus the remaining 5, the result is 85.

The second type: the mantra method.

This formula method is suitable for the addition of two digits within 100, and there is an addition of carry. This kind of addition, because of the occurrence of the full ten forward such a situation, primary school students are particularly prone to error, therefore, there is a mantra to remember, namely:

Add 9 to subtract 1, add 8 to subtract 2, add 7 to subtract 3, add 6 to subtract 4, add 5 to subtract 5, add 4 to subtract 6, add 3 to subtract 7, add 2 to subtract 8, add 1 to subtract 9. In practice, it should be noted that the number of additions in the formula is the number of single digits.

For example, 52+39, first observe the single digits of the two added numbers, and there is a plus 9, then, you have to subtract 1 from the single digit 2 of 52, and the result is 1, and the calculation of the ten digits must first advance to one, add 5 and 3, and the final result is 91.

Correspondingly, if it is a two-digit abdication subtraction, there is also a formula, namely: minus 9 to add 1, minus 8 to add 2, minus 7 to add 3, minus 6 to add 4, minus 5 to add 5, minus 4 to add 6, minus 3 to add 7, minus 2 to add 8, minus 1 to add 9. In the same way, the subtraction in the mantra refers to the number of subtracting the single digit.

For example, 42-19, at this time, it is necessary to use the formula, subtract 9, give 42 digits of 2, add 1 to become 3, after that, the ten digits first retreat one, and then use 4 to retreat one, the remaining 3 to subtract 1, and the final result is equal to 23.

The third type: the acceleration and deceleration algorithm of the dislocation number.

What is a misalignment?

For example, 28 and 82, 39 and 93, such numbers are misplaced numbers.

When subtracting the number of dislocations, there is a quick calculation trick, which is to first subtract the number of dislocations and tens, and finally, use the difference of subtraction, and then multiply it by 9, which is the result of the subtraction of this set of dislocation numbers.

For example, e.g. 91-19=? The method is to take 9-1 to equal 8, and then multiply 8 by 9, and the result is 72. Isn't it easy?

Primary school students do more questions, do more questions of the same type, do them repeatedly, do different types of questions crossed, do them repeatedly, practice makes perfect, and improve the ability to calculate, these are the foundations, and the knowledge after the foundation is solid is easy to master.

1. Moving with symbols.

When a calculation problem has only the same level of operations (only multiplication and division or only addition and subtraction) and no parentheses, we can "move with the buried symbols".

2. Bracket method.

When adding parentheses to addition and subtraction operations, the parentheses are preceded by a plus sign, the parentheses are unchanged, the parentheses are preceded by a minus sign, and the parentheses are changed. When adding parentheses to the multiplication and division operation, the parentheses are preceded by the multiplication sign, the parentheses are unchanged, the parentheses are preceded by the division sign, and the parentheses are changed by the sign.

3. Remove the bracket method.

When removing parentheses in addition and subtraction operations, the parentheses are preceded by a plus sign, and the parentheses are removed without changing the sum sign, and the bracket is preceded by a minus sign.

4. Distribution method.

In parentheses is an addition or subtraction operation, multiplying with another number, pay attention to the distribution.

5. Extract the common factor.

Note the extraction of the same factor.

6. Clever division is multiplication.

Dividing by a number is equal to multiplying by the reciprocal of this number.

7. Split term method.

Fractional splitting refers to splitting the items in the fraction equation so that the split items can be offset before and after.

Primary 6 Mathematics General Review Material (6).

Class: Name:

1. Oral arithmetic of the following questions. (23 points).

2. Write down the laws or properties used in simple calculations for each of the following questions (12 marks).

3. Calculate in a simple way. (65 points).

1) Fifty-two and eleven twenty-fifths seventy-nine and eleven twenty-tenths

2+2+2+2+……2+2 (2000 numbers from 3-2002, so there are 1000 2s) +2+1

4 and 5 both use a conversion formula 1 (a b) = 1 (b-a) (1 a-1 b).

For example, 1 15 = 1 (3 5) = 1 (5-3) (1 3-1 5) = 1 2 (2 15) = 1 15 can be verified.

4) (1 2/2) + (2 1/3) + (3 4/1) + ....10 11 in 11).

5) One-third + one-fifteenth + one-thirty-fifth + sixty-third + ninety-nine.

6) One and a half - five sixths + seven twelves - ninety tenths + eleven thirty - thirteen forty-two + fifteen fifty-sixths.

According to the hint, 1 and 1 2 = 1 + 1 2, +1 2 + 1 3 = 5 6 ......)

If you look closely, it won't be difficult, and it can be easily calculated. Take a look at it yourself, some questions will be better calculated into scores, I'm not in the sixth grade, I don't know if you learn the same as us, I can only find some, sorry, please forgive me.

2222 multiplied by 29/100 minus 3333 multiplied by 1/25 plus multiplied by 9/10

Multiplicative distributive property].

This is a series of equal differences, fainting, high school knowledge].

Multiplicative distributive property].

Multiplicative distributive property].

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This question is not suitable for simple calculations, and if you have to do simple calculations, you can only do it reluctantly: