GCF (HCF) of 39 and 42

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What is the Greatest Common Divisor of 39 and 42?

Answer

GCF (HCF) of 39 and 42 is
3

Common factors: 1, 3

3 divides both: 39 ÷ 3 = 13, 42 ÷ 3 = 14 — and 13 and 14 share no factor but 1, so no larger number divides both.

39 = 3 × 13

42 = 2 × 3 × 7

Prime3942Lowest power
2—2—
3333
7—7—
1313——

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

GCF = 3

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GCF Table

Number 1Number 2GCF
39401
39411
39423
39431
39453
39461
39471
39483
39491
39513
395213
39531
39543
39561
396513
3913013

FAQ

What is the Greatest Common Divisor of 39 and 42?

GCF (HCF) of 39 and 42 is 3

How to find the GCF of 39 and 42?

You can find the GCF of 39 and 42 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 39 and 42 is 3.

What prime factors do 39 and 42 share?

The prime factorizations of 39 and 42 have 3 in common, and multiplying those shared primes gives 3 — exactly the greatest common factor.

How does the GCF reduce the fraction 39/42?

Divide the numerator and the denominator by the GCF 3: 39 ÷ 3 = 13 and 42 ÷ 3 = 14. So 39/42 in lowest terms is 13/14.

See Also