GCF for 18, 39 and 45

"Greatest Common Factor of 3 Numbers" Calculator
Greatest Common Factor of
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What's the Greatest Common Factor (GCF) of 18, 39 and 45?

Answer

GCF of 18, 39 and 45 is
3

Common factors: 1, 3

3 divides all three: 18 ÷ 3 = 6, 39 ÷ 3 = 13, 45 ÷ 3 = 15 — and 6, 13 and 15 have no factor but 1 common to all of them, so no larger number divides all three.

18 = 2 × 32

39 = 3 × 13

45 = 32 × 5

Prime183945Lowest power
22———
3323323
5——5—
13—13——

— = 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

1st2nd3rdGCF
1830393
1831391
1832391
1833393
1834391
1835391
1836393
1837391
1838391
1839393
1839401
1839411
1839423
1839431
1839441
1839453
1839461
1839471
1839483
1839491
1839501
1839513
1839521
1839531
1839543
1839551
1839561
1839573
1839581
1839591

FAQ

What's the Greatest Common Factor (GCF) of 18, 39 and 45?

GCF of 18, 39 and 45 is 3

What prime factors do 18, 39 and 45 share?

All three factorizations contain 3, and multiplying those shared primes gives 3 — exactly the greatest common factor.

Can you get the GCF of 18, 39 and 45 two numbers at a time?

Yes. The GCF of 18 and 39 is 3, and the GCF of 3 and 45 is 3 — the same answer, because the greatest common factor is associative and does not depend on the order of the three numbers.

How does the GCF simplify the ratio 18 : 39 : 45?

Divide every term by the GCF 3: 18 ÷ 3 = 6, 39 ÷ 3 = 13 and 45 ÷ 3 = 15. So 18 : 39 : 45 in lowest terms is 6 : 13 : 15, and no whole number other than 1 divides all three of those.

See Also