I have decided to outline a 16-week Philippine Civil Service Review (PCSR) series in mathematics. This way, you will be able to study systematically. In this series, I will post links every week, give exercises, and discuss the solutions of the exercises. Included in the links are articles that I have written and Taglish Youtube videos that I have created.

Let’s start our review in mathematics by learning about GCD and LCM. These two concepts are very important since you will use them in solving problems involving fractions. Fractions appear everywhere in the Civil Service exams. Be sure that you master these concepts before we proceed to our Week 2 review.

**LEAST COMMON MULTIPLE**

Least Common Multiple (LCM) is used when adding, subtracting, comparing and ordering, fractions. Here are the links with examples.

**Articles**

**Youtube Videos**

**GREATEST COMMON DIVISOR**

Greatest Common Divisor (GCD) is used in factoring and reducing fractions to lowest terms. GCD is also called Greatest Common Factor (GCF)

Articles

Youtube Videos

- Part 1: Understanding Common Divisors
- Part 2: Common Divisors and Greatest Common Divisors
- Part 3: Exercises on Getting the GCD
- Part 4: Getting the GCD by Prime Factorization
- Part 5: GCD and Reducing Fractions to Lowest Terms

Enjoy!

If you have questions about the articles and the videos just post them below.