Math 1 Lesson: Round numbers

### 1.1. Knowledge to remember

– Recognize round numbers, read, write, compare decimal numbers.

– Identify how many tens and 0 units are in a round number structure.

### 1.2. Mathematical forms on Round numbers

**Form 1: Read and write round numbers**

How to read a round number: I read the number tens and pair it with the word “ten”, except for the number 10 số

How to write a round number: I write the tens digit and write in the units line 0

**Form 2: Comparison of round numbers**

The larger the tens digit, the larger the value of that number.

**Form 3: Analysis of the structure of tens**

A round number always consists of a tens and 0 units.

### 1.3. Solving Textbook Exercises page 127

**Lesson 1 page 127 **

Write according to the pattern

b) Thirty: 30 Forty:….

Eight dozen: …. Six dozen: ….

One dozen:…..Fifty:…..

c) 20: two dozen 50:……….

70:…dozen 80:………

90:…dozen 30:………

__Solution method__

Read and write decimals according to the pattern.

**Solution guide**

a)

WRITE READING NUMBERS

20 Twenty

10 Ten

90 Ninety

70 Seventy

READING NUMBERS WRITING NUMBERS

Sixty 60

Eighty 80

Fifty 50

Thirty 30

b) Thirty : 30 Forty : 40

Eight dozen : 80 Sixty : 60

A dozen : 10 Fifty : 50.

c) 20: two dozen 50: fifty

70: seven dozen 80: eight dozen

90: ninety 30: Three dozen.

**Lesson 2 page 127**

Round number ten?

__Solution method__

Count forward or backward by 10 units and then fill in the missing number in the blank.

__Solution guide__

**Lesson 3 page 127**

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

20….10 40….80 90….60

30….40 80….40 60….90

50….70 40….40 90….90

**Solution method**

Compare the round numbers, the larger the number with the tens, the larger the value, then fill in the appropriate sign.

__Solution guide__

20 > 10 40 < 80 90 > 60

30 < 40 80 > 40 60 < 90

50 < 70 40 = 40 90 = 90

### 1.4. Solving Textbook Exercises page 128

**Lesson 1 page 128**

Concatenation (according to the pattern):

**Solution method**

Match the reading with the appropriate decimal numbers.

__Solution guide__

**Lesson 2 page 128**

Write (in the form):

a) The number 40 consists of 4 tens and 0 units.

b) Number 70 includes…tens and …units.

c) The number 50 includes…tens and…units.

d) Number 80 includes…tens and ….units.

__Solution method__

Parse round numbers into tens and units.

__Solution guide__

b) Number 70 includes 7 tens and 0 units.

c) The number 50 consists of 5 tens and 0 units.

d) The number 80 consists of 8 tens and 0 units.

**Lesson 3 page 128**

a) Circle the smallest number: 70 , 40 , 20 , 50 , 30 .

b) Circle the largest number: 10, 80, 60, 90, 70.

__Solution method__

Compare the tens digits and then circle the required number.

__Solution guide__

a) Circle the number 20.

b) Circle the number 90.

**Lesson 4 page 128**

__Solution method__

Compare the given numbers and write them in order.

**Solution guide**

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