Math 2 Lesson: 38 + 25

### 1.1. Knowledge to remember

### 1.2. Math forms

**Form 1: Performing the calculation**

– Set in vertical columns, numbers in the same row are placed straight together.

– Perform the addition of the numbers of each row in order from right to left.

**Form 2: Compare**

– Find the value of both sides (Form 1)

– Compare the numbers found in the order of comparison of the digits of the rows, from tens to units.

**Form 3: Math Quiz**

– Read and analyze the problem: Determine the given data, the amount of increase or decrease and the requirements of the problem.

– Find a solution: When the problem requires finding the value of “both” or “all”, I often use addition.

– Presentation of the solution: Write the solution, calculation and answer to the problem.

– Check the solution of the problem and the results just found.

### 1.3. Textbook exercise solution page 21

**Lesson 1**

Calculate:

__Solution method__

Perform calculations with numbers in order from right to left.

__Solution guide__

Lesson 2

Write the correct number in the blank:

__Solution method__

Add two terms and then fill in the result in the blank.

__Solution guide__

lesson 3

Line segment AB is 28dm long, line segment BC is 34dm long. How many decimeters does the ant have to travel from A to C?

__Solution method__

**Summary**

Line segment AB : 28dm

Line segment BC : 34dm

Line segment AC = …dm?

**The answer**

Want the length of line segment AC, we take the length of line segment AB plus the length of line segment BC.

__Solution guide__

The long-distance ant is:

28 + 34 = 62 (dm)

Answer 62dm.

Lesson 4

Enter the sign >; < or = in the empty box:

8 + 4 … 8 + 5 18 + 8 … 19 + 9

9 + 8 … 8 + 9 18 + 9 … 19 + 8

9 + 7 … 9 + 6 19 + 10 … 10 + 18

__Solution method__

– Calculate the value of both sides.

– Compare the values and then fill in the appropriate mark in the blank box.

__Solution guide__

### 1.4. Textbook Exercises Page 22

Lesson 1

Mental arithmetic:

8 + 2 = 8 + 3 = 8 + 4 = 8 + 5 =

8 + 6 = 8 + 7 = 8 + 8 = 8 + 9 =

18 + 6 = 18 + 7 = 18 + 8 = 18 + 9 =

__Solution method__

Add up the numbers and fill in the blanks with the result.

__Solution guide__

8 + 2 = 10 8 + 3 = 11 8 + 4 = 12 8 + 5 = 13

8 + 6 = 14 8 + 7 = 15 8 + 8 = 16 8 + 9 = 17

18 + 6 = 24 18 + 7 = 25 18 + 8 = 26 18 + 9 = 27

Lesson 2

Calculate then calculate:

38 + 15; 48 + 24; 68 + 13; 78 + 9; 58 + 26.

__Solution method__

– Set calculation: Write the addition so that the digits in the same row and column together.

Calculation: Add numbers from right to left.

__Solution guide__

lesson 3

Solve the problem according to the following summary:

Package of lemon candy : 28 pieces

Package of coconut candy : 26 pieces

Both packages : … which?

__Solution method__

To find the solution, we take the number of candies in the package of lemon candy plus the number of candies in the package of coconut candy.

__Solution guide__

Both packages have the number of candies:

28 + 26 = 54 (piece)

Answer: 54 candies.

Lesson 4

Number?

__Solution method__

– Perform calculations from left to right and then fill in the results in the empty box.

– Count in turn until the last empty cell.

__Solution guide__

Lesson 5

Circle the letter in front of the correct answer:

28 + 4 = ?

A. 68

B. 22

C. 32

D. 24

__Solution method__

Do the addition calculation and then choose the correct answer.

__Solution guide__

28 + 4 = 32.

**Circle the letter C.**

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