Browse Tag: greatest common factor

Review for August 2019 has already started

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

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The Difference Among LCM, LCD, GCD and GCF


LCM means Least Common Multiple. Multiple in this context is used for integers. LCD, on the other hand, means Least Common Denominator. As we know, denominator is used in fractions.

So, in 1/3 and 1/4, should we say, LCM or LCD?

CORRECT STATEMENT: LCM of 3 and 4 (multiple is used for integers).
CORRECT STATEMENT: LCD of 1/3 and 1/4 (denominator is used for fractions).

It is INCORRECT to say LCM of 1/3 and 1/4.

Notice that the LCM of 3 and 4 and the LCD of 1/3 and 1/4 is 12. That’s why most people use them interchangeably.


GCF means Greatest Common Factor

A factor of an integer is an integer that can be multiplied with another integer to get the given integer. For example, 3 is a factor of 6 because 3 x 2 = 6.

A divisor of an integer is an integer that divides that integer (without a remainder). For example, 3 is a divisor of 6 because 6/3 = 2, which is an integer.

Basically, factors and divisors have the same meaning when it comes to integers. Factor, however, is the term used in multiplication, while divisor is the term used for division. Here are some examples.

Positive factors of 12 are 1, 2, 4, 6, 12.
Positive divisors of 12 are 1, 2, 4, 6, 12.

GCF and GCD have the same meaning and will give the same values.

PCSR Civil Service Exam Review Guide 1

Updated: April 25, 2017




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




Lesson 1: Least Common Multiple Part 1
Lesson 2: Least Common Multiple Part 2
Lesson 3: Least Common Multiple Part 3


C. Proper, Improper, and Mixed Form

D. More on LCM and GCD


A. Vocabulary

Tip: Try to memorize the words and use it in your own words.

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

C. Spelling

Civil Service Review Spelling Quiz 1

Part III: CLERICAL Operations (Subprofessional)

Alphabetizing Rules Part 1


Greatest Common Factor Quiz

After learning How to Get the Greatest Common Factor of Two Numbers, let’s have a quiz! The greatest common factor is used to reduce a fraction to lowest terms, so I included such items on the quiz below.

To reduce a fraction to lowest terms, get the greatest common factor of the numerator and the denominator, and then divide

Greatest Common Factor Quiz

Part 1: Get the greatest common factor of the following numbers.

1.) 12 and 15
[toggle title=”Answer”]3[/toggle]

2.) 18 and 28  Continue Reading

How to Get the Greatest Common Factor of Numbers

The numbers that can divide an integer is called its factor or divisor. For example, the factors of 4 are 1, 2, and 4 because these are the numbers that divide 4 without having a remainder. Another example is 6 which has factors 1, 2, 3, and 6. It is clear that each number has always 1 and itself as factors. Note that in this discussion, when I say number, I mean positive integer.

If we select more than one number, we can observe that they have common factors (just like having common multiples). Let’s have the following examples.  Continue Reading

How to Convert Percent to Fraction

In Civil Service Examinations, as well as other examinations in basic mathematics, knowing how to convert  percent, fractions, and decimals to each other is very advantageous especially if you can do it mentally. Let us try with the following example.

A P640 shirt is marked 25% discount. How much will you have to pay for it?

It seems that you need a pencil for this problem, but you can actually do it in your head. Read it to believe it.

The equivalent of 25% in fraction is 1/4, therefore, you have to take away the fourth of the price. Now, 1/4 of 640 seems difficult but what if we try to split it to 600 + 40? Now, 1/4 of 600 is 150, which means that from the 600, you have 450 left. Now, 1/4 of 40 is 10, which means that you have 30 left. So, 450 + 30 is 480 and that is the discounted price of the t-shirt. Continue Reading

How to Get the Greatest Common Factor of Numbers

A tutorial on how to get the greatest common factor of two numbers. In this video, the concept of factors was briefly explained. A simple application of greatest common factor which is converting fractions to lowest terms was also illustrated.

Errata: In example 2, 9 is also a factor of 45. In example 3, 2 is also a factor of 42. Sorry, I just thought of the given while doing the video.

For more videos, please visit the PH Civil Service Reviewer channel on Youtube.