1. Section 2-1
Factors

2. Objectives
Students will be able to identify prime and composite numbers.
Students will be able to state the greatest common factor (GCF).

3. Vocabulary
Divisible: when a number can be divided by another number and has a remainder of 0.
Factor: a number that “goes into” another number evenly. (the number can be divided by the factor evenly).
Prime Numbers: A whole number greater than 1 with exactly two factors: 1 and itself!
Composite Numbers: A whole number greater than one with more than two factors.
*** 1 is neither prime nor composite***
Prime Factorization: A composite number written as a product of prime numbers.
Greatest Common Factor: (GCF) The largest factor of both numbers that is the same

4. Example 1 Write the prime factorization of 54: 54 2 27 3 9 3 3
3 9
3 3
54 = 2*33

5. Example 2 Find the GCF of 42 and 36 42 36 1 • 42 1 • 36 2 • 21 2 • 18
1 • • 36
2 • • 18
3 • • 12
6 • • 9
6 • 6
Steps!
Identify all the factors of each number
Circle all the factors that are common
Identify the largest circled number

6. You Try! Find the Prime Factorization of 63.
Find the GCF of: 54 and 63
Find the GCF of: 18 and 42
State if each of the following are Prime of Composite!