1.   Based on the factor trees, what is the greatest common factor of 8 and 20?
    A. 2 B. 8
    C. 20 D. 4
    Hint

  2.   What is the greatest common factor of 25a2b and 5ab2?
    A. 5 B. 5a2b2
    C. 5ab D. 5ab2
    Hint

  3.   What is the greatest common factor of 39 and 18?
    A. 9 B. 6
    C. 13 D. 3
    Hint

  4.   What is the greatest common factor of 36, 54, and 90.
    A. 6 B. 18
    C. 9 D. 36
    Hint

  5.   Janice has three pieces of string that are 36 cm, 24 cm, and 18 cm in length. She needs to have strings that are all the same length, but she does not want to waste any string. What is the greatest length Janice can cut each piece of string into and still have equal lengths?
    A. 6 cm B. 3 cm
    C. 9 cm D. 12 cm
    Hint



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