Toán lớp 2 phép cộng có nhớ: Khái niệm, hướng dẫn giải các dạng bài tập liên quan

The forms of Mathematics 2nd Mathematics remember is an important part of the child's base math program. Grasping this, timhieulichsuquancaugiay.edu.vn has summarized 5 common math forms and the most detailed solution. This is to support parents to review math at home for children more easily.

The concept of additional mathematics remember class 2

Before learning about knowledge about the addition of additional subtraction, remember the second grade, let timhieulichsuquancaugiay.edu.vn review the definition of the addition as well as the elements inside it.

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Addition and elements to grasp

The addition calculation is usually written by the symbol of “+” is one of the four basic operations of arithmetic, including: addition, subtraction, multiplication and division. The result of the addition of natural numbers is the total value of those numbers.

In the plus calculation we need to pay attention to two important elements, the term and total, represented as shown below:

The concept of units, tens, hundreds

In order to easily solve the forms of Mathematics of the 2nd Mathematics with a memory within 100, children need to understand the concepts of the unit class (including: unit, tens, hundreds). More specifically, you can guide your child through the examples below:

The concept of 2 -digit additional additions in primary mathematics

In the primary mathematics, the addition of the addition is that the addition of the terms of a certain row will have results greater than 10.

This is also the most basic way to add multi -digit numbers. Specifically, the implementation will be the arrangement of terminals vertically and plus each column starting from the unit column to the right. If a column is greater than or equal to 10, the remaining digit is “remembered” to the next column.

For example, the total calculation of 12 plus 88 below:

How to solve the type 2 mathematics plus common memory

There are many ways to teach maths with 2nd grade, the easiest is for children to do the forms of exercises. Here are the most common types of problems in the program or 2nd grade exams.

Form 1: Calculation

Exercise 1: Calculation

Instructions for solving: First we need to consider the terms in the calculation to see if there is something more special. For example, there are units of 0, or dozens and units equal to 0, …. After that, we can perform the plus calculation as usual.

Example: 20 + 30 + 40 =?

Comment: We can easily see that the unit's unit in all three numbers in this calculation is 0, so we only need to care about the digits dozens.

We have: 2 + 3 + 4 = 9, write 9. Then, write the number 0 after the number 9. The final result of the calculation will be: 90.

Exercise 2: Write the next 3 numbers in the sequence

Instructions for solving: Find the rules of the sequence (increasing, decreasing). Next is to find the rules of numbers in the sequence (increase or decrease how many units). Finally, find the missing numbers and fill in the blank.

For example: 10; 20; 30; 40; …; ….; …;

Comment: This is a row of numbers increasing gradually because from the second number in the sequence, it will be equal to the number before it plus 10.

So immediately after 40 will be 40 + 10 = 50. Do the same with the rest we will get the sequence: 10; 20; 30; 40; 50; 60; 70.

Form 2: Perform calculation

Exercise 1: Set calculated and calculate

Instructions for solving:

• The digits in the same row will be straightened together (hundreds of hundreds, tens of tens of tens and units in line).

• Starting the addition of the memory from the smallest numbers (from the unit, to tens, hundreds, …).

Illustrative example:

Comment (first calculation): We have: 9 + 3 = 12, write 2 remember 1; Next we have: 1 + 4 = 5 Remember 1. The final result is 62. The same solution for the remaining calculations.

See also: Tips parents for the most easy -to -understand mathematical math tips at home

Exercise 2: Circle the letter before the best answer

Instructions for solving: This type of exercise is similar to the above. But it will be a sequence of plus calculations, and we will perform sequential calculations from left to right. After finding the final result, circling the most accurate answer.

For example: 241 + 124 + 201 =?

A. 665; B. 566; C. 656; D. 666

Comment: This is a calculation with 3 terms, and each term is 3 -digit number. Therefore, this calculation can be separated into 2 calculations.

So the answer will be B. 566

Form 3: Compare

Exercise: Fill in the () suitable for the blank

Instructions for solving:

Method 1: Calculate the sum

Initially we will calculate the sum of one side, then bring the result comparison with the other side, finally fill in the appropriate mark into the blank.

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Example: 42 + 100 … 124

We perform calculations: 42 + 100 = 142; Compare 124 and 124, 142 greater than 124.

Inferred 42 + 100> 124

Method 2: Separate numbers

Separation has a number into a sum, so that there are some rows equal to some of the other classes. Compare the remaining terms between the two sides. Finally, fill in the appropriate sign.

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Example: 42 + 100 … 124

We make separation No. 124 = 24 + 100 (of which, both sides have a number of rights on the right side of 100); Comparing the remaining two terms is 24 and 42, 42> 24.

So 42 + 100> 24 + 100 → Inferred: 42 + 100> 124

Form 4: Find the unknown ingredient of calculation

Exercise 1: Find x

Instructions for solving: Determine the role of x (deductible number). If the must be some, then perform the calculation as usual. If the must be a sum, then the sum of it first and then find x

For example:

Exercise 2: Fill in the missing digit into the sign *

Instructions for solving: Also based on the principle of calculating and calculating, we do from right to left, from the smallest to the largest.

Note: If the * sign is in the sum, we perform plus as usual. But if the * sign is located in a certain digit at the term, then we take the number of the number at the sum minus the number of the goods in the remaining term.

Example: * 5 + 42 = 7 *

• The * sign is in the first term of the first term and the unit's row.

• We have, the star sign in the unit of the total = 5 + 2 = 7.

• The star mark is in the first dozens of the first term = dozens of the sum – dozens of the second term = 7 – 4 = 3

So, the full calculation will be: 35 + 42 = 77

Form 5: Fast calculation

Exercise: Calculated by convenient

Instructions for solving: bringing the numbers round tens or hundreds. After that, groups of terms together, using the basic properties of addition, including: Common, combined.

Example: 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9

We see: 1 + 9 = 10; 2 + 8 = 10

Similar to the remaining terms, we get a sequence of numbers as follows:

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 = 1 + 9 + 2 + 8 + 3 + 7 + 4 + 6 + 5 + 5 = 10 + 10 + 10 + 10 + 5 = 45 = 45

The secret to studying mathematics of grade 2 additional memory effectively

In order to help children learn well the knowledge of additional calculations, parents can support their children through the following methods and secrets:

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Help your baby master the 2nd grade memory math rules

For calculations with 2nd grade when done, it will mainly rely on the rule “If a column is greater than or equal to 10, the remaining digit is” remembered “to the next column”. Therefore, parents need to explain and guide detailed instructions to gradually solve calculations so that their children can easily understand and absorb this knowledge instead of speaking. Specifically:

• Step 1: Parents let the baby write the operations in the form of vertical columns (Note dozens to exactly dozens, rows of units to correct units of 2 terms).
• Step 2: Carry out the addition of addition/subtraction from the unit to dozens from right from right to left.

Note: If the plus calculation is in a large unit or equal to 10, you should take the number in the unit to put down the results, while tens will plus the number in the previous dozen to become an accurate result.

Let me do the homework for the second layer, remember from reality

To help children easily visualize this type of math, parents can take exercises related to reality and ask the baby to try. For example, parents can puzzle for example, children have 15 candies, mothers give 6 more pills to ask how many tablets do you have? Initially, parents should ask their children to calculate the right results after the baby can practice counting the number of candies on their hands. Because with some large calculations you cannot count in the traditional way.

Practice children, practice math homework with 2nd grade

In order to improve the effectiveness of 2nd grade mathematics, remember for children, parents should ask the baby to practice and practice regularly. The practice here may come from doing homework assigned in class, in textbooks, learn more new knowledge on the internet, organize math games to increase children's interest, …

Regular practice will help stimulate the child's brain thinking better, along with increasing the ability to acquire, memorize and apply when solving math or application in practice more accurately.

Some 2nd grade math exercises in addition to remember to let the baby practice

Here are some exercises on the problems of additional 2nd grade so that they can practice themselves effectively:

Lesson 1: Class 2A has 34 students, class 2B has 29 students. Calculate the total number of students of 2A and 2B classes.

Lesson 2: An has 29 candies, Mom gives An 5 candy. How many candies are there now?

Lesson 3: Set calculated then calculate

a) 6 + 37

b) 26 + 5

c) 56 + 6

d) 86 + 8

e) 67 + 9

f) 6 + 66

g) 5 +86

h) 56 + 4

i) 66 + 7

j) 57 + 18

k) 16 + 27

l) 57 + 16

m) 46 + 18

n) 58 + 16

Lesson 4: Calculation:

a) 6 + 5 = ……..

b) 6 + 7 = ……..

c) 9 + 6 = ……..

d) 6 + 9 = ……..

e) 6 + 4 = ……..

g) 8+ 5 = ……..

h) 9 + 6 = ……..

i) 6 + 4 + 3 = ……..

j) 9 + 1 + 8 = ……..

k) 8 + 2 + 10 = ……..

Lesson 5: Find x, know

a) x + 34 = 54

b) 38 + x = 68

c) 42 + x = 89

d) x + 62 = 96

e) x + 21 = 26 + 15

g) 22 + x = 39 + 36

h) x + 33 = 37 + 38

Lesson 6: Summarize with the diagram and solve the following problem: Last month, my nest 36 points ten. Calculating the score ten months ago less than this month 7 points. Calculate the score of 10 months?

Lesson 7: Fill in the seal>,

a) 26 + 5 … 17 + 9

b) 12 + 8 … 15 + 5

c) 17 + 9 … 24 + 8

d) 18 + 64 … 25 + 27

Lesson 8: Fill in the appropriate number in the box:

Lesson 9: Write the appropriate number in the blank:

Lesson 10: Three people go fishing, the first person can catch 9 fish. The second person has 17 fish. The third person can catch 15 fish. Calculate the total number of fish that three people can catch.

Above is a summary of the concepts and 5 types of mathematics of the 2nd layer with common memory. However, if you want your child to experience modern educational methods such as interactive comics, math learning through games, … then you can immediately refer to the application of math learning in English timhieulichsuquancaugiay.edu.vn Math!

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