1. Greatest Common Factor (GCF) and Least Common Multiple (LCM)
Objective:
Find the greatest common factor and Least common multiple of 2 or more factors.

2. The greatest common factor(s) of two or more numbers is the Greatest Common Factor (GCF).
When solving for GCF think of all the numbers that you can multiply to get a specific number. When done draw a “horse shoe”.
Example 1: Find the Greatest Common Factor or GCF of 18 and 48.
Factors of 18: 1 x = 1, 2, 3, 6, 9, 18
2 x 9
3 x 6
Factors of 48: 1 x = 1, 2, 3, 4, 6, 8, 12, 16, 24, 48
2 x 24
3 x 16
4 x 12
6 x 8
The common factors of 18 and 48 are 1, 2, 3, and 6.
So, the greatest common factor ( or GCF) is 6.
Your Example: Find the GCF of 10 and 30.

3. A least common multiple (LCM) is the lowest multiple that two or more numbers share.
Example : Find the least common Multiple (LCM) of 2 and 8.
Multiples of 2: 2, 4, 6, 8, 10, 12, 14, ... Multiples of 8: 8, 16, 24, 32, 40, 48, 56, ...
The Least Common Multiple would be 8.
Your Example: Find the LCM of 10 and 30.

4. Homework:
Find the GCF of each set of numbers.
12, 78
32, 48
40, 50
45, 75
18, 36
Find the LCM of each set of numbers.
1. 6, 8
2. 4, 6
3. 12, 20
4. 9, 12
5. 8, 14