6th Grade Math Textbook, Progress

Find the GCF. Use prime factorization.

24. 48 and 56 25. 64 and 96 26. 36 and 72 27. 80 and 100


25. 45 and 75 29. 39 and 104 30. 48 and 84 31. 100 and 125


26. 14, 49, and 70 33.48, 80, and 112 34.18, 54, and 90

Find a pair of numbers:

35. Between 10 and 20 that have 6 36. Between 12 and 18 that have 4
    as their GCF. as their GCF.


36. Between 15 and 30 that have 5 38. Between 16 and 24 that have 8
    as their GCF. as their GCF.

9

27

3 
 3 
 3

3

54

9 
 6

3 

 3 3 
 2

39. Can the greatest common factor of 8 and 32 be greater than 8?
    Explain your reasoning.

Find the GCF Using Prime Factorization

Find the GCF of 27 and 54.

• First use factor trees to find the prime factors of each number.
  Finding the prime factors of a number is called prime factorization.


• Then multiply the prime factors that are common to both to find the GCF.

common to both

27  3 
 3 
 354  2 
 3 
 3 
 3

3 
 3 
 3  27

GCF of 27 and 54: 27

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