Subtraction within 9

### 1.1. Knowledge to remember

– How to do subtraction within 9

– Represent the situation in the figure by calculation and application of subtraction just learned to real problems.

### 1.2. Maths for Subtraction within 9

**Form 1: Performing the calculation**

Calculate the value of subtractions within 9.

**Type 2: Calculates the value of an expression containing multiple addition and subtraction operations phép**

If an expression contains two or more addition and subtraction operations, you perform the calculations from left to right.

**Form 3: Fill in the missing element in the calculation**

Repeat the learned addition and subtraction of numbers within 9 and then fill in the missing number or sign in the blank.

### 1.3. Solve textbook exercises pages 78, 79

**Lesson 1 page 78**

Calculate:

**Solution method**

Perform the subtraction along the column and then write the result in the blank.

__Solution guide__

**Lesson 2 page 79**

Calculate:

8 + 1 = 7 + 2 = 6 + 3 = 5 + 4 =

9 – 1 = 9 – 2 = 9 – 3 = 9 – 4 =

9 – 8 = 9 – 7 = 9 – 6 = 9 – 5 =

__Solution method__

Add or subtract numbers and write the results in the blanks.

__Solution guide__

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

9 – 1 = 8 9 – 2 = 7 9 – 3 = 6 9 – 4 = 5

9 – 8 = 1 9 – 7 = 2 9 – 6 = 3 9 – 5 = 4

**Lesson 3 page 79**

Number?

__Solution method__

– Write 9 as the sum of the numbers (follow the pattern in the first column) and then fill in the missing number in the blank.

– Perform calculations in the direction of the arrows and then write the results in the appropriate blanks.

__Solution guide__

**Lesson 4 page 79**

Write the appropriate calculation:

__Solution method__

– Count all the bees in the picture, the number of bees that flew away and the number of bees left in the hive.

– Write the correct word calculation from the numbers.

**Solution guide**

The proper calculation is: 9 – 4 = 5

### 1.4. Solving Textbook Exercises page 80

**Lesson 1 page 80**

Calculate:

8 + 1 = 7 + 2 = 6 + 3 = 5 + 4 =

1 + 8 = 2 + 7 = 3 + 6 = 4 + 5=

9 – 8 = 9 – 7 = 9 – 6 = 9 – 5 =

9 – 1 = 9 – 2 = 9 – 3 = 9 – 4 =

**Solution method**

Perform the calculation and then fill in the blank with the result.

__Solution guide__

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

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

9 – 8 = 1 9 – 7 = 2 9 – 6 = 3 9 – 5 = 4

9 – 1 = 8 9 – 2 = 7 9 – 3 = 6 9 – 4 = 5

**Lesson 2 page 80**

Number ?

5 + …. = 9 9 – …. = 6 …..+ 6 = 9

4 + …. = 8 7 -…… = 5 …..+ 9 = 9

…..+ 7 = 9 …..+ 3 = 8 9 – ……= 9

__Solution method__

Repeat the calculations within 9 learned and then write the missing number in the blank.

__Solution guide__

5 + 4 = 9 9 – 3 = 6 3 + 6 = 9

4 + 4 = 8 7 – 2 = 5 0 + 9 = 9

2 + 7 = 9 5 + 3 = 8 9 – 0 = 9

**Lesson 3 page 80**

Put the appropriate <, >, = in the dot:

5 + 4 ….9 6…..5 + 3 9 – …..8

9 – 2…..8 9……5 + 1 4 + 5…..5 + 4

__Solution method__

– Calculate the value of the calculated sides.

Compare and then fill in the blanks with the appropriate mark.

__Solution guide__

5 + 4 = 9 6 < 5 + 3 9 - 0 > 8

9 – 2 < 8 9 > 5 + 1 4 + 5 = 5 + 4

**Lesson 4 page 80**

Write the appropriate calculation:

__Solution method__

Count the number of chickens, the number of chickens outside and the number of chickens in captivity, then write the appropriate calculation.

__Solution guide__

The calculation is: 9 – 6 = 3.

**Lesson 5 page 80**

How many squares are there in the figure?

**Solution method**

Count the number of small squares, jigsaw puzzles and continue counting until the end.

**Solution guide**

There are 5 squares (Figure 1; 2; 3; 4 and figure 1 + 2 + 3 + 4).

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