Table of units for measuring mass

### 1.1. Knowledge to remember

#### 1.1.1. Decagram, hectogram

To measure the mass of objects weighing tens and hundreds of grams, people also use the following units: *decagram, hectogram.*

Decagram is abbreviated as dag. Hectogram is abbreviated as hg. 1dag = 10g 1hg = 10dag 1hg = 100g |

#### 1.1.2. Table of units for measuring mass

ton |
weights |
oats |
kg |
hg |
dag |
g |

1 ton = 10 quintals |
1 quintal = 10 yen |
1 nest = 10 kg |
1 kg = 10 hg |
1 hg = 10 dag |
1 dag = 10 g |
1 g = \(\frac{1}{{10}}\) dag |

Two contiguous units of mass are 10 times inferior to each other; 1 previous unit is 10 times higher than the next unit and vice versa; Each unit of mass corresponds to a row of digits.

#### 1.1.3. How to change

- Based on the unit of measurement table. (1 VND/previous position is 10 times higher than dong/next position).

__ For example:__ 1 quintal = 100 kg so 8 quintal = 800 kg.

- Multiply, divide, divide. (For smaller units, multiply by the number of folds; for larger units, divide by the number of times)

__ For example:__ 1 quintal = 100kg so 23 quintals = (23 x 100)kg = 2300kg; 2300kg = (2300 : 100)weight = 23 quintals.

123kg = 100kg + 20kg + 3kg = 1 quintal 2 oats 3kg = 100kg + 23kg = 1 quintal 23kg.

- Based on each unit of measure corresponds to 1 row of digits. (add, remove digit 0).

__ For example:__ 56 quintals = 5600kg ; 12000 kg = 120 quintals ; 12000 kg = 12 tons.

### 1.2. Solving Textbook Exercises

**Lesson 1:** Write the correct number in the dot

a) 1dag = … g 1hg = … dag

10g = … dag 10dag =… hg

b) 4dag = … g 3kg = … hg 2kg 300g = … g

8hg = … dag 7kg = … g 2kg 30g = … g.

**Solution guide:**

- Based on the table of units of measurement đo

a) 1dag = 10g 1hg = 10dag

10g =1 dag 10dag = 1hg

b) 4dag = 40g 3kg = 30 hg 2kg 300g = 2300g

8hg = 80dag 7kg = 7000g 2kg 30g = 2030g

**Lesson 2:** Calculate

380g + 195g 452hg x 3

928dag – 274dag 768hg : 6

__Solution guide:__

- Perform calculations as for natural numbers, then add units of measure to the result.

380g + 195g = 575g 452hg x 3 = 1356hg

928dag – 274dag = 654dag 768hg : 6 = 128hg

**Lesson 3:** Put >, <, = in the dot

5dag … 50g 4 weights 30kg … 4 weights 3kg

8 tons … 8100kg 3 tons 500kg … 350kg

__Solution guide:__

- Convert the measurements to the same unit of measure and compare the results.

+) We have: 1dag = 10g so 5dag = 50g.

+) 4 weights 30kg = 430kg; 4 weights 3kg = 403kg

Which: 430kg > 403kg. So: 4 weights of 30 kg > 4 weights of 3 kg.

+) 8 tons = 8000kg

Which: 8000kg < 8100kg. So: 8 tons < 8100 kg.

+) 3 tons 500kg = 3500kg

Which: 3500kg > 350kg. So: 3 tons 500 kg = 350kg

We have the following result:

5dag = 50g 4 weights 30kg > 4 weights 3kg

8 tons < 8100kg 3 tons 500kg = 350kg

**Lesson 4:** There are 4 packages of cakes, each weighing 150g and 2 packs of candy, each weighing 200g. How many kilograms of cake and candy are there in all?

__Solution guide:__

- Calculate the weight of 4 cakes = weight of 1 cake × 4.
- Calculate the weight of 2 packs of candy = weight of 1 pack of candies × 2.
- Calculate the total weight of 4 packages of cake and 2 packages of candy = weight of 4 packages of cake + weight of 2 packages of candy.
- Convert the measurement you have just found to the unit of measurement of kilograms, note that we have: 1kg = 1000g.

*Solution*

4 pack cake weight is:

150 × 4 = 600 (g)

2 packs of candy weight are:

200 × 2 = 400 (g)

The total number of kilograms of cake and candy is:

600 + 400 = 1000 (g)

1000g = 1kg

Answer: 1kg.

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