Download Unit 2: Decimals: Lesson 7: Dividing Decimals

Unit 2: Understanding Positive Real Numbers
Lesson 4: Greatest Common Factor
Vocabulary:
 greatest common factor (GCF)- the largest shared factor of two or more whole numbers
Finding the GCF
Example 1: Find the GCF of the following set of numbers: 16 and 24
Method #1: LISTING
Step #1: List all factors of both numbers
Factors of 16: 1, 2, 4, 8, 16
Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
Step #2: Underline the common factors.
Factors of 16: 1, 2, 4, 8, 16
Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
Step #3: Circle the Greatest Common Factor (GCF).
Factors of 16: 1, 2, 4, 8, 16
Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24
Method #2: LADDER DIAGRAM (SLIDE METHOD)
Step #1: Make a ladder diagram for BOTH numbers.
Step #2: Keep making the ladder until the only common factor is 1.
ONE AND YOU’RE DONE. 
Step #3: Multiply the numbers down the left side
2x2x2 =8
*The GCF of 16 and 24 is 8.
TRY THESE (Find the GCF of each set of numbers using any method you prefer.):
1.)
18 and 27
2.)
32 and 72
3.)
42, 56
4.)
30, 60
5.) The math clubs from 2 schools agreed to a competition. Members from each club must be divided into teams and the teams from
all clubs must be equally sized. What is the greatest number of teams that can be made if Georgia has 24 members and Texas has 72
members? How many members on each team would be from Georgia? How many members on each team would be from Texas?