1. Copyright ©Ed2Net Learning, Inc.1 Greatest Common Factor Grade 6

2. Copyright ©Ed2Net Learning, Inc.2 Warm Up 1) 139 Determine whether each number is prime or composite 2) 1700 3) 17 4) 333

3. Copyright ©Ed2Net Learning, Inc.3 Lets review what we have learned in the last lesson When a whole number, greater than one has only 2 factors, 1 and whatever your number is, it is called a Prime Number. When a whole number greater than one has more than 2 factors it is called a Composite Number. The numbers 0 and 1 are neither Prime or Composite.

4. Copyright ©Ed2Net Learning, Inc.4 The number 60 is a composite number. It can be written as the product 2 x 2 x 3 x 5. 2, 3 and 5 are factors of 60 and all these factors are prime numbers. We call them prime factors. When we express a number as a product of prime factors, we have actually factored it completely. We refer to this process as prime factorization Review

5. Copyright ©Ed2Net Learning, Inc.5 Lets take an Example 280 2 140 2 70 2 35 7 5 So, the Prime Factorization of 280 expressed as a product of Factors looks like this … 2 x 2 x 2 x 7 x 5 Simplified to: 2 3 x 7 x 5 Factor Tree of 280 7 and 5 are Prime numbers so cannot be factored further

6. Copyright ©Ed2Net Learning, Inc.6 Lets Get Started! Greatest Common Factor (GCF) of two or more numbers can be defined as the greatest number that is a factor of each number Two methods can be used to find GCF

7. Copyright ©Ed2Net Learning, Inc.7 List the factors of each number. Then identify the common factors. The greatest of these common factors is the GCF. Find the GCF of 27 and 36 List all the factors of both the numbers Factors of 27 : 1, 3, 9, 27 Factors of 36 : 1, 2, 3, 4, 6, 9, 12, 18, 36 Common factors 1, 3, 9 Thus, the GCF of 27 and 36 is 9 Method 1

8. Copyright ©Ed2Net Learning, Inc.8 Write the prime factorization of each number. Then identify all common prime factors and find their product, the GCF Lets take the same example to find the factors of 27 and 36 Write the prime factorization 2736 3 x 9 3 x 12 3 3 x 3 3 x 4 3 3 2 x 2 Method 2

9. Copyright ©Ed2Net Learning, Inc.9 Lets take another example Find the GCF of 63 and 42 Method 1 List the factors 63:1, 3, 7, 9, 21, 63 42:1, 2, 3, 6, 7, 14, 21, 42 Since the common factors are 1, 3, 7 and 21 the GCF is 21

10. Copyright ©Ed2Net Learning, Inc.10 Method 2 Write the prime factorization 63 42 9 x 7 6 x 7 3 x 3 x 7 2 x 3 x 7 The common prime factors are 3 and 7 so the GCF is 3 x 7 = 21 Finding GCF of 63 and 42

11. Copyright ©Ed2Net Learning, Inc.11 Now you try some Find GCF of the following numbers 1) 36 and 48 2) 160 and 550 3) 20a2 and 14ab 4) 36, 24, 144, 96

12. Copyright ©Ed2Net Learning, Inc.12 Break Time

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14. Copyright ©Ed2Net Learning, Inc.14 1)The high school marching band has 75 members. If they line up in equal rows, how many rows of how many band members can march together?

15. Copyright ©Ed2Net Learning, Inc.15 2) What would be the greatest number of crayons in each row of an 8 64 and a 96 crayon box, if all rows have the same number.

16. Copyright ©Ed2Net Learning, Inc.16 3) Can the GCF of a set of numbers equal to one of the numbers itself? Explain

17. Copyright ©Ed2Net Learning, Inc.17 Let us review what we have learnt today Greatest Common Factor of two or more numbers can be defined as the greatest number that is a factor of each number We can find the GCF by using two methods

18. Copyright ©Ed2Net Learning, Inc.18 List the factors of each number. Then identify the common factors. The greatest of these common factors is the GCF. Method 1 Write the prime factorization of each number. Then identify all common prime factors and find their product, the GCF Method 2

19. Copyright ©Ed2Net Learning, Inc.19 Find the GCF of these set of numbers 66 and 72a) b) 10, 20, 35 c) 9, 11

20. Copyright ©Ed2Net Learning, Inc.20 Great Job Done Be sure to practice what you have learned today