GCF (HCF) of 6 and 21

"Greatest Common Factor" Calculator

What is the Greatest Common Divisor of 6 and 21?

Answer

GCF (HCF) of 6 and 21 is

Common factors: 1, 3

3 divides both: 6 ÷ 3 = 2, 21 ÷ 3 = 7 — and 2 and 7 share no factor but 1, so no larger number divides both.

6 = 2 × 3

21 = 3 × 7

Prime	6	21	Lowest power
2	2	—	—
3	3	3	3
7	—	7	—

— = power 0: the prime is not a factor of this number, so it cannot be in the GCF.

GCF = 3

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Related Calculations

GCF Table

Number 1	Number 2	GCF
6	4	2
6	5	1
6	7	1
6	8	2
6	9	3
6	10	2
6	11	1
6	12	6
6	13	1
6	14	2
6	15	3
6	16	2
6	17	1
6	18	6
6	20	2
6	21	3
6	24	6
6	25	1
6	26	2
6	27	3
6	29	1
6	30	6
6	32	2
6	33	3
6	35	1
6	36	6
6	37	1
6	39	3
6	40	2
6	42	6

FAQ

What is the Greatest Common Divisor of 6 and 21?

GCF (HCF) of 6 and 21 is 3

How to find the GCF of 6 and 21?

You can find the GCF of 6 and 21 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 6 and 21 is 3.

What prime factors do 6 and 21 share?

The prime factorizations of 6 and 21 have 3 in common, and multiplying those shared primes gives 3 — exactly the greatest common factor.

How does the GCF reduce the fraction 6/21?

Divide the numerator and the denominator by the GCF 3: 6 ÷ 3 = 2 and 21 ÷ 3 = 7. So 6/21 in lowest terms is 2/7.

GCF (HCF) of 6 and 21

What is the Greatest Common Divisor of 6 and 21?

More with these numbers

Related Calculations

See Also

GCF Table

FAQ

What is the Greatest Common Divisor of 6 and 21?

How to find the GCF of 6 and 21?

What prime factors do 6 and 21 share?

How does the GCF reduce the fraction 6/21?

See Also

Number 1	Number 2	GCF
6	4	2
6	5	1
6	7	1
6	8	2
6	9	3
6	10	2
6	11	1
6	12	6
6	13	1
6	14	2
6	15	3
6	16	2
6	17	1
6	18	6
6	20	2
6	21	3
6	24	6
6	25	1
6	26	2
6	27	3
6	29	1
6	30	6
6	32	2
6	33	3
6	35	1
6	36	6
6	37	1
6	39	3
6	40	2
6	42	6

Number 1	Number 2	GCF
6	4	2
6	5	1
6	7	1
6	8	2
6	9	3
6	10	2
6	11	1
6	12	6
6	13	1
6	14	2
6	15	3
6	16	2
6	17	1
6	18	6
6	20	2
6	21	3
6	24	6
6	25	1
6	26	2
6	27	3
6	29	1
6	30	6
6	32	2
6	33	3
6	35	1
6	36	6
6	37	1
6	39	3
6	40	2
6	42	6

Number 1	Number 2	GCF
6	4	2
6	5	1
6	7	1
6	8	2
6	9	3
6	10	2
6	11	1
6	12	6
6	13	1
6	14	2
6	15	3
6	16	2
6	17	1
6	18	6
6	20	2
6	21	3
6	24	6
6	25	1
6	26	2
6	27	3
6	29	1
6	30	6
6	32	2
6	33	3
6	35	1
6	36	6
6	37	1
6	39	3
6	40	2
6	42	6