GCF (HCF) of 6 and 15

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What is the Greatest Common Divisor of 6 and 15?

Answer

GCF (HCF) of 6 and 15 is
3

Common factors: 1, 3

3 divides both: 6 ÷ 3 = 2, 15 ÷ 3 = 5 — and 2 and 5 share no factor but 1, so no larger number divides both.

6 = 2 × 3

15 = 3 × 5

Prime615Lowest power
22——
3333
5—5—

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

GCF = 3

See Also

FAQ

What is the Greatest Common Divisor of 6 and 15?

GCF (HCF) of 6 and 15 is 3

How to find the GCF of 6 and 15?

You can find the GCF of 6 and 15 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 6 and 15 is 3.

What prime factors do 6 and 15 share?

The prime factorizations of 6 and 15 have 3 in common, and multiplying those shared primes gives 3 — exactly the greatest common factor.

How does the GCF reduce the fraction 6/15?

Divide the numerator and the denominator by the GCF 3: 6 ÷ 3 = 2 and 15 ÷ 3 = 5. So 6/15 in lowest terms is 2/5.