GCF-LCM Homework - page 1

Name ______________

Find the greatest common factor (GCF) of these pairs of numbers:
1. Write out the factors of both numbers to their right.
2. Find the biggest one that appears in both lists and circle it.

1).
Factors of 34: ___________________
Factors of 14: ___________________

GCF = _____		 2).
Factors of 51: ___________________
Factors of 17: ___________________

    GCF = _____
3).
Factors of 42: ___________________
Factors of 9: ___________________

    GCF = _____


 4).
Factors of 18: ___________________
Factors of 12: ___________________

    GCF = _____
5).
Factors of 30: ___________________
Factors of 42: ___________________

    GCF = _____		 6).
Factors of 24: ___________________
Factors of 36: ___________________

    GCF = _____

Find the least common multiple (LCM) of these pairs of numbers by using the LCM formula:
(Use your calculator!)

LCM(a,b) = (a x b) / GCF(a,b)
The pairs of numbers below are the same as above, so you can use the GCFs you found to find their LCM:

7).
LCM (34,14) = (34 x 14) / _____ = _____
 8).
LCM (51,17) = _______________ = ____
9).
LCM (42,9) = _______________ = _____

 10).
LCM (18,12) = _______________ = ____
11).
LCM (30,42) = _______________ = ____		 12).
LCM (24,36) = _______________ = ____