Question

Find the greatest common factor and the least common multiple of 16 and 20. The prime factorizations of each number are given.

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Answer 1

GCF 4, LCM 80

Explanation:

Since both 16 and 20 have two 2s as factor, their greatest common factor is 4.

The LCM is found by multiplying all of the remaining factors by the LCM:

16 still has (2 x 2), 20 still has (5), times the GCF (4) so 2 x 2 x 5 x 4 = 80.