How to calculate addition and subtraction within fifty using the method of making up to ten

Split the large number and make up the small number;

Split the decimal number and make up the large number.

Carry addition within 20:

Children should keep in mind that "9 to 1", "8 to 2", "7 to 3", "6 to 4", "5 to 5" The method of making up ten is simple and easy, and the thinking process has "one look (look at the big number), two split (split the decimal number), three make up the ten, and add the rest of the number" Look at the big number, divide the decimal number, make up the ten, and add the remaining number.

The method of making up to 10 is very useful when doing addition operations up to 20. Let's learn the following with the teacher

Let's do the math first, 10+1=? ，9+8=？Baby, which one do you prefer? It must be the same as the teacher, the first one, why is that?

Because 10 plus a few equals a dozen, which is very easy to calculate.

But in real calculations, not all questions have 10s, which is not easy to calculate. It doesn't matter, there's no 10, we just want to find a way to make up 10.

Now to calculate 9+8, who can we make up to 10? 9 or 8 can be made into 10, split the big to make up for the small, we make up 9 to 10 from 10, let 8 points give 9 a 1, there is 7 left.

1 and 9 are good friends, good friends have to hold hands, good friends first. 9+1=10, plus 8 to the remaining 7, 10+7= 8 is closer to 10, and 8 is 2 from 10, 7 gives 8 a 2, and there is 5 left. Count the good friends first, plus the remaining 5,8+7=15.

The method of making up ten and breaking ten is the most commonly used method for calculating the addition and abdication subtraction within 20, which has the characteristics of strong regularity, easy to understand and simple process. He has strategies such as splitting decimals, making up large numbers, and splitting large numbers to make decimals, which are the basis for learning carry addition within 20, abdication subtraction, and further learning deeper addition and subtraction. In addition, addition and subtraction within 20 is an implicit oral arithmetic teaching content, which requires children to quickly and reasonably split and assemble various calculation information in their minds to get correct results.

It is through such mental activities that the Ten Methods and the Ten Methods are used to exercise thinking, develop attention, instantaneous memory, and creative thinking abilities. To learn carry addition and abdication subtraction within 20 with the method of making up ten and breaking ten, children are first required to have the following knowledge reserves: 1. Be proficient in calculating addition and subtraction within 10 (proficient in calculating decomposition within 10, proficient in memorizing complements) 2. Be proficient in calculating 10+*= such as 10+3=13.

3. Be proficient in decomposing 10---20 numbers, such as 13, which can be divided into 10 and 3; 15 can be divided into 10 and 5 and so on.

The addition and subtraction within 50 is as follows:Subtraction formula1. Minus - minus = difference.

2. Difference + subtraction = subtraction.

3. Minus - difference = minus.

Subtraction-related properties.

1. Anti-exchange rate: subtraction is anti-exchange, if a and b are any two numbers, then (a-b)=-b-a).

2. Anti-associativity: Subtraction is anti-associative, and when trying to redefine subtraction, then a-b-c=a-(b+c).

Addition and subtraction within fifty is taught to children as follows:

1) Carry addition within 50: the same digit alignment, add from the single digit, the full ten of the single digit should be advanced to the ten digit, and the number on the ten digit is added, don't forget to add the one that comes in.

2) Abdication subtraction within 50: the same digit alignment, subtract from the single digit, when the single digit does not carry the stove enough to reduce, you should borrow one from the ten digits, and then subtract each other, don't forget to borrow one when the number on the ten digits is subtracted.

There is no need to deliberately teach addition and subtraction within 50. At first, you can learn addition and subtraction within 10, and after you are familiar with this, you can learn addition and subtraction within 20. The addition and subtraction of the advance and retreat within 20 are converted into those within 10 by using the method of making up the ten and the method of borrowing the ten methods of annihilation.

There will be no problem in learning less than 50 below, and there is a previous foundation.

1.Let's start with an integer.

2.Teaching children is to be patient and not rushed. The comprehension ability of the child is not enough, and parents can use some things to teach their children to add and count. For example, with small sticks, small biscuits, and so on. Arouse children's interest and they will be more confident in learning.

3.Don't deliberately teach arithmetic, you can experience it in life.

Addition and subtraction within 50 belongs to the knowledge content of mathematics in the first grade of primary school, addition and subtraction within 50 requires students to be proficient in calculation methods, and can be calculated accurately and quickly for calculation problems, then, how to teach with counting fingers, before counting fingers, students must be proficient in counting 1 to 50 These numbers are practiced, generally we use the method of continuing to teach, such as how much is a number plus another number?

We start with the first number and count upwards as much as we add so that the students can easily figure out the number.

The addition and subtraction within 50 is as follows:The laws of addition and subtraction are as follows:1. The commutative law of addition.

The two numbers are added to exchange the position of the added number, and the sum is unchanged, which is represented by letters as a+b=b+a.

2. Associative law of addition.

Add three numbers, add the first two numbers first, or add the last two numbers first, and the sum is unchanged, which is expressed by letters as (a+b)+c=a+(b+c).

3. The nature of subtraction.

Subtracting a number is equal to adding the opposite of the number, a-b = a + (-b).

Subtracting a number plus adding a number is equal to subtracting the difference between the two numbers, a-b+c=a-(b-c).

In continuous subtraction, the two subtractions are added up first, and then the sum of the two subtractions is subtracted from the subtracted number, and the difference remains unchanged, a-b-c=a-(b+c).

The mantra for carry addition within 20 is: "Add nine minus one, add eight minus two, add seven minus three, add six minus four, add five minus five." Take "plus nine minus one" as an example, "plus nine minus one" refers to the addition of a number to 9, and subtract 1 from this number as the single digit of their sum.

The subtraction formula for abdication within 20 is to convert abdication subtraction within 20 into addition within 10. The recipe is: "Subtract nine plus one, minus eight plus two, minus seven plus three, minus six plus four, minus five plus five."

Learning to calculate doesn't have to be rushed. If your baby has not learned to count before the age of three, then there is no need to rush to give him addition. After learning to count from 1 to 10, we can teach the baby to add within 10.

1. Start with points to learn addition. In the initial stage, the baby can not understand the concept of "plus", and must use the method of points to find the answer, so parents should allow the baby to use points to do the calculation.

2. Learn addition and subtraction orally, without using written formulas.

Written calculations contain a lot of symbols that are still unfamiliar to your baby, and pushing your baby with a bunch of incomprehensible abstract symbols at the beginning will increase his stress and boredom. The best way to do this is to do it in a chatty tone.

Addition:

Subtraction:

The law of intersectional change and the law of union1. The addition of rational numbers also has a commutative and associative property (the same as the commutative and associative properties of integers), which are expressed by letters as:

Commutative law: a+b=b+a two numbers are added, and the position of the added number is exchanged, and the sum is unchanged.

Associative law: a+b+c=(a+b)+c=a+(b+c).

2. Add the three numbers in the hall, first add the two numbers of the front dress, or add the last two numbers first, and the same as the same.

Addition and subtraction within 50 is the foundation of children's learning of mathematics, and can be taught to calculate by the following methods:

Number cognition: First of all, we must teach or Hu children to recognize the number 0 50 and be able to identify it accurately and quickly. Teaching aids such as number cards and number puzzles can be used to help children learn numbers.

The basic concept of addition: Addition is the process of adding two or more numbers, which can be demonstrated with an object, such as having a child put two toy cars together and then count how many cars there are.

Calculation method of addition: You can let the child use his fingers to calculate, for example, for 3+2, first let the child use his fingers to represent 3, then use his fingers to represent 2, and finally add the two groups of fingers together to count 5.

The basic concept of subtraction: Subtraction is the process of subtracting another number from one number, and the same can be demonstrated with items, such as asking a child to take 3 out of 10 toy candies and see how many are left.

How to calculate subtraction: You can also let your child use his fingers to calculate, for example, for 10-3, let him use his finger to indicate 10, then subtract 3, and count the remaining numbers.

Practice: After mastering the basic addition and subtraction concepts and calculation methods, you can let your child practice well, such as giving your child some simple addition and subtraction problems, asking him to do the calculations by himself, and checking whether the answers are correct.

It should be noted that in the process of teaching children to calculate, it is necessary to pay attention to keeping children interested and focused, and giving encouragement and praise to improve children's learning enthusiasm and self-confidence.

Additive operations. 1. Add two numbers with the same sign, take the same symbol as the additive, and add the absolute value.

2. If the absolute value is equal, the sum of the two numbers of the opposite number is 0; If the absolute values are not equal, take the sign of the addition with the greater absolute value, and subtract the smaller absolute value from the larger absolute value.

3. Add two numbers that are opposite to each other to get 0.

4. Add a number to 0 and still get this number.

5. Two numbers that are opposite to each other can be added first.

6. Numbers with the same symbol can be added first.

7. Numbers with the same denominator can be added first.