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Greatest Common Factor

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Greatest Common Factor

Calculate the Greatest Common Factor or GCF of 28, 32 and 72

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The instructions to find the GCF of 28, 32 and 72 are the next:

1. Decompose all numbers into prime factors

28	2
14	2
7	7
1

32	2
16	2
8	2
4	2
2	2
1

72	2
36	2
18	2
9	3
3	3
1

2. Write all numbers as the product of its prime factors

Prime factors of 28	=	2² . 7
Prime factors of 32	=	2⁵
Prime factors of 72	=	2³ . 3²

3. Choose the common prime factors with the lowest exponent

Common prime factors: 2

Common prime factors with the lowest exponent: 2²

4. Calculate the Greatest Common Factor or GCF

Remember, to find the GCF of several numbers you must multiply the common prime factors with the lowest exponent.

GCF = 2² = 4

Also calculates the:

Least Common Multiple or LCM of 28, 32 and 72

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