## GCD Practice Exercises with Solutions on Youtube

Find the GCD/GCF of the following numbers.

1. 12, 18

2. 14, 35

3. 20,28

4. 25, 30, 40

5. 7, 12

6. 48, 72

7. 42, 60, 72

8. 24, 36

9. 12, 16

10. 18, 30, 54

PH Civil Service Exam Reviewer

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Find the GCD/GCF of the following numbers.

1. 12, 18

2. 14, 35

3. 20,28

4. 25, 30, 40

5. 7, 12

6. 48, 72

7. 42, 60, 72

8. 24, 36

9. 12, 16

10. 18, 30, 54

After a one-month break, we have already started our review series for the month of August 2019. The date of the examination will be on August 7, 2019. If you wish to follow our review series (I suggest you do), please like and then follow the Philippine Civil Service Exam Reviewer Facebook page. Every week, we post Math, English, and Clerical tutorials and practice questions. For the first week our topics are LCM, GCD, Subject Verb agreement. You may download the review outline here.

We have already posted new video tutorials in Filipino on LCM and GCD on the Sipnayan Youtube channel.

** Greatest Common Divisor/Greatest Common Factor**

- GCD01 Divisors, Common Divisors, and Greatest Common Divisor
- GCD02 Finding the GCD of Two or More Numbers by Listing
- GCD03 Getting the GCD Using the Ladder Method
- GCD04 The Difference Between GCD and GCF
- GCD05 Finding the GCF by Prime Factorization (Without Exponents)
- GCD06 Finding the GCF by Prime Factorization (with Exponents)
- GCD07 Finding the GCF Using Factor Trees
- GCD08 Using GCD to Reduce Fractions to Lowest Terms

Week 1: September 24 – October 1, 2017

This week, we are going to learn about Least Common Multiple (LCM) and Greatest Common Divisor (GCD). LCM is needed in adding and subtracting dissimilar fractions, while GCD is needed in reducing fractions to lowest terms. In addition to LCM and GCD, we will also learn about converting improper fractions to mixed number and vice versa.

PART I: MATHEMATICS

A. GCD

Youtube Tutorial Videos (Taglish)

Lesson 1: Understanding Common Divisors

Lesson 2: Common Divisors and Greatest Common Divisor

Lesson 3: Exercises on Getting the GCD

Lesson 4: Getting the GCD by Prime Factorization

Lesson 5: GCD and Reducing Fractions to Lowest Terms

Tutorial Articles

B. LCM

Youtube Tutorial Videos (Taglish)

Lesson 1: Least Common Multiple Part 1

Lesson 2: Least Common Multiple Part 2

Lesson 3: Least Common Multiple Part 3

Tutorial Article

How to Get the Least Common Multiple of Numbers

C. Lowest Terms, Improper Fractions and Mixed Form

Youtube Tutorial Videos (Taglish)

- Reducing Fractions to Lowest Terms
- How to Convert Improper Fractions to Mixed Number
- How to Convert Mixed Fractions to Improper Fractions

Tutorial Articles

- How to Reduce Fractions to Lowest Terms
- How to Convert Improper Fractions to Mixed Number
- How to Convert Mixed Fractions to Improper Fractions

D. More about LCM and GCD

Difference between LCM and GCD

PART II: ENGLISH

A. Vocabulary

Civil Service Exam Vocabulary Review Part 1

B. Grammar

Lesson 1: Verb and Tenses: An Introduction

Lesson 2: The Subject-Verb Agreement Rules Part 1

Lesson 3: The Subject-Verb Agreement Rules Part 2

Lesson 4: Subject-Verb Agreement Exercise

C. Spelling

Civil Service Review Spelling Quiz 1 Set 2

Part III: CLERICAL (Subprofessional)

PART III: TIPS AND TRICKS

7 Tips on Answering Reading Comprehension Questions

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After learning about LCM and GCD in our **PCSR Review Guide 1**, let’s practice what we have learned by answering the exercises below.

1.) What is the LCM of 6 and 8?

2.) What is the LCM of 3, 4, and 9?

3.) Consider the following sequences:

Sequence 1: 4, 8, 12, 16, 20, 24, 28, …

Sequence 2: 5, 10, 15, 20, 25, 30, …

As we can see, 20 is common to both sequences. What is the 10th common number?

4.) Gina goes to BODY SLIM gym every 3 days, while Sam goes to the same gym every 4 days. If they were in the same gym on a February 12, what’s the nearest date that they will be both in the gym?

5.) In a decoration LED light, the green lights blink every 400 milliseconds, the blue light every 500 milliseconds, and the red light every 750 milliseconds. If the three lights all blinked at the same time, in how many milliseconds will they again blink at the same time?

6.) What is the LCD of 1/3, 1/4, and 1/6?

7.) What is the GCD of 28 and 35?

8.) What is the GCD of 39, 65, and 91?

9.) A rectangular paper with dimensions 12 inches by 18 inches is to be cut into largest possible squares of equal sizes. If no paper is to be wasted, what should be the dimensions of the squares?

Q10.) A rectangular prism piece of wood with dimensions 16 inches by 20 inches by 32 is to be cut into cubes of the same size.

A. If we want to minimize the wasted wood while cutting, what should be the dimensions of the cubes?

B. How many cubes can we make given the above conditions?

**Solutions and Answers**

1.) 24

2.) 36

3.) 200

4.) LCM of 3 and 4 is 12. Twelve days after February 12 is** February 24**.

5.) 6000 milliseconds

6.) 12

7.) 7

8.) 13

9.) Side of the square should be GCD of 12 and 18 which is **6 inches**.

10.) A. Side of the cube should be GCD of 16, 20, and 32 which is equal to **4 inches**.

B. 16/4 × 20/4× 32/4 = 4 × 5 × 8 = 160 cubes

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After learning work problems, we now learn how to answer mixture problems.

**PART I: MATH**

A. Videos

Mixture Problem Part 1

Mixture Problem Part 2

Mixture Problem Part 3

Mixture Problem Part 4

B. Articles

How to Solve Mixture Problem Part 1

How to Solve Mixture Problem Part 2

How to Solve Mixture Problem Part 3

How to Solve Mixture Problem Part 4

How to Solve Mixture Problem Part 5

**Part II: ENGLISH**

Civil Service Exam Vocabulary Review 13

Part III: For Review Guides 1-23, click here.

After learning age problems in **PCSR Review Guide 10**, let us now learn motion problems. Motion problems are problems that deal with distance, rate, and time. Watch the videos below and read the articles. From Wednesday to Saturday this week, I will post 10-15 practice problems.

PART I: MATH

A. Videos

- Introduction to Motion Problems
- How to Solve Motion Problems Part 1
- How to Solve Motion Problems Part 2
- How to Solve Motion Problems Part 3
- How to Solve Motion Problems Part 4
- How to Solve Motion Problems Part 5

B. Articles

- Introduction to Motion Problems
- How to Solve Motion Problems Part 1
- How to Solve Motion Problems Part 2
- How to Solve Motion Problems Part 3
- How to Solve Motion Problems Part 4

Part II: ENGLISH

A. Vocabulary

Civil Service Exam Vocabulary Review 10

B. Grammar

B.1A Subject-verb agreement Practice Test

B.1B Subject-verb agreement Answers

B.2A Grammar and Correct Usage Practice Test

B.2B Grammar and Correct Usage Answers

After learning how to solve number problems, let’s learn how to solve age problems. Watch the videos below and read the articles. Then, we will have exercise later.

PART I: MATH

A. Videos (These videos are in Taglish and the links point to Youtube).

How to Solve Age Problems Part 1

How to Solve Age Problems Part 2

How to Solve Age Problems Part 3

How to Solve Age Problems Part 4

How to Solve Age Problems Part 5

How to Solve Age Problems Part 6

How to Solve Age Problems Part 7

How to Solve Age Problems Part 8

B. Articles

How to Solve Age Problems Series

How to Solve Age Problems Part 1

How to Solve Age Problems Part 2

How to Solve Age Problems Part 3

C. Exercises

Practice Exercises

Solutions to Practice Exercises

Part II ENGLISH

A. Vocabulary

B. Reading Comprehension

7 Tips in Answering Reading Comprehension Questions

For those who are searching the Review Guides 1 to 9, you can find them **here**.

**PART I: MATH**

A. Youtube Videos (All videos are in Taglish)

**How to Solve Number Problems Mentally**

How to Solve Number Problems Mentally 1

How to Solve Number Problems Mentally 2

How to Solve Number Problems Mentally 3

**How to Solve Word Number Problems**

How to Solve Word Number Problems Part 1

How to Solve Word Number Problems Part 2

How to Solve Word Number Problems Part 3

**How to Solve Consecutive Number Problems **

How to Solve Consecutive Number Problems Part 1

How to Solve Consecutive Number Problems Part 2

How to Solve Consecutive Number Problems Part 3

B. Articles. You can read the articles below.

How to Solve Number Word Problems

The Solving Number Word Problems Series

How to Solve Number Word Problems Mentally

How to Solve Number Word Problems Part 1

How to Solve Number Word Problems Part 2

How to Solve Number Word Problems Part 3

How to Solve Number Word Problems Part 4

**How to Solve Consecutive Number Problems **

How to Solve Consecutive Number Problems Part 1

How to Solve Consecutive Number Problems Part 2

How to Solve Consecutive Number Problems Part 3

**Part II ENGLISH**

A. Vocabulary

Civil Service Exam Vocabulary Review 8

B. Grammar and Correct Usage

How to Use the Articles A, An, and The

When to use the Pronouns I and me

Enjoy your review!