1. MENTAL MATH Provide the missing operations: 4 ___ 2 = 2 5____3 = 8
15 _____3 = 5
24 _____2 = 48
10 _____2 = 5
42 _____6 = 7
8 _____8 = 0

2. GREATEST COMMON FACTOR
Every number has at least two factors: 1 and the number itself. Numbers such as 18 and 24 have several factors in common.
We are looking for the greatest common factor of 18 and 24.
You need to list all the factors of each number, from the least to the greatest.

3. FACTORS
Factors that are shared by two or more numbers are called common factors.
The greatest of the common factors of two or more numbers is the greatest common factor (GCF) of the numbers.
To find common factors, you can make a list.

4. FACTORS OF 18 1 , 2. 3 6 9 and 18. FACTORS OF 24
FACTORS IN COMMON
1, 2, 3, and 6
GREATEST COMMON FACTOR
Their greatest common factor is 6.

5. LET’S PRACTICE Identify the common factors of 16 and 24.
Factors of Factors of 24
1 X x 24
2 X x 12
4 X x 8
4 x 6
The common factors are 1, 2 4 and 8.

6. Identify the common factors of each set of numbers.
25, 60
18, 27, 36
15, 45
12, 19
32, 48
12, 66
11, 44
12, 21, 30
3, 12, 18
4, 10, 14