IXL | Greatest common factor of three or four numbers | 6th grade math

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What is the greatest common factor of 12, 9, and 18?

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question

What is the greatest common factor of 8, 16, and 12?

key idea

The greatest common factor is the largest whole number that is a factor of each of two or more numbers.

solution

Write the prime factorization for each number.

8	=	2 × 2 × 2

16	=	2 × 2 × 2 × 2

12	=	2 × 2 × 3

Next, find the common factors shared by all of the numbers.

8	=	2 × 2 × 2

16	=	2 × 2 × 2 × 2

12	=	2 × 2 × 3

Finally, multiply the common factors to find the greatest common factor.

2 × 2 = 4

The greatest common factor of 8, 16, and 12 is 4.

Looking for more? Try these:

Lesson: Greatest common factor

Lesson: Prime factorization

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Not feeling ready yet? These can help:

F.6Greatest common factor

F.2Identify factors

F.4Prime factorization

Lesson: Greatest common factor

Lesson: Prime factorization