1. DRILL
1.) ( ) ÷ 8 = 2.) 769 x 112 = 3.) $12.00 – t = $ ) A regular hexagon has 6 sides of equal length. If the perimeter of a hexagon is 150 in., how long is each side?

2. Finding The Greatest Common Factor
LESSON 20

3. Greatest Common Factor
The greatest common factor is the largest common factor of two numbers. Factors are all of the numbers that divide into a given number equally.
The greatest common factor can be found by comparing all the factors of two numbers or by finding the prime factorization of two numbers

4. Finding Factors
Finding the factors of a number can be done by sequentially dividing numbers into the product. When the factors begin to repeat you have found all factors.

5. We are now back to 6. We have found all factors of 18.
Finding Factors
Find the factors of 18
1 goes into 18, 18 times.
2 goes into 18, 9 times.
3 goes into 18, 6times.
4 does not divide 18 evenly.
5 does not divide 18 evenly.
We are now back to 6. We have found all factors of 18.
1, 2, 3, 6, 9 and 18

6. Finding The GCF Using Factors
Determine the greatest common factor of two numbers by finding all the factors for the two numbers then comparing them. The largest common factor of the two numbers is their greatest common factor.

7. The greatest common factor is of 36 and 24 is 12
Using Factors
Find the GCF of 36 and 24
Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18 and 36
Factors of 24: 1, 2, 3, 4, 6, 8, 12 and 24
The greatest common factor is of 36 and 24 is 12

8. The greatest common factor of 15 and 100 is 5
Using Factors Again
Find the GCF of 15 and 100
Factors of 15: 1, 3, 5 and 15
Factors of 100: 1, 2, 4, 5, 10, 20, 25,
50 and 100
The greatest common factor of 15 and 100 is 5

9. The greatest common factor of 25 and 50 is 25
Using Factors Again
Find the GCF of 25 and 50
Factors of 25: 1, 5 and 25
Factors of 50: 1, 2, 5, 10, 25, and 50
The greatest common factor of 25 and 50 is 25

10. Greatest Common Factor
Now you know how to find the greatest common factor you if you have any other questions check out these sites about finding the GCF
Greatest Common Factor
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