SOLUTION: Please help. Thank you Choose the correct greatest common factor of 105 and 147 a) 21 b) 15 c) 63 d) 20

Question 117738: Please help. Thank you
Choose the correct greatest common factor of 105 and 147
a) 21 b) 15 c) 63 d) 20
Found 2 solutions by MathLover1, jim_thompson5910:
Answer by MathLover1(20849) (Show Source): You can put this solution on YOUR website!
The of two or more whole numbers is the that into each of the numbers.

There are to find the greatest common factor.

The is to list all of the factors of each number, then list the and choose the .

the of and :
the factors of are ,, , , , , and
thefactors of are ,,,, and
the factors of and are , ,,
Although the numbers in bold are all common factors of both and , is the greatest common factor.
The for finding the greatest common factor is:
to list the, then the

The prime factorization of and is:

Notice that the prime factorizations of and both have one and one in common.
So, we simply these common prime factors to find the greatest common factor:

so, correct answer is: a)

Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
First, list the prime factorization of each number. If you need help with prime factorization, check out this solver.

105: 3*5*7

147: 3*7*7

Now highlight the factors that the two numbers share in common

105: 3*5*7

147: 3*7*7

Now pick one set of these highlighted numbers and multiply

3*7=21

So the GCF of 105 and 147 is 21

So the answer is A)

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