GCF for 18, 27 and 45

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What's the Greatest Common Factor (GCF) of 18, 27 and 45?

Answer

GCF of 18, 27 and 45 is
9

Common factors: 1, 3, 9

9 divides all three: 18 ÷ 9 = 2, 27 ÷ 9 = 3, 45 ÷ 9 = 5 — and 2, 3 and 5 have no factor but 1 common to all of them, so no larger number divides all three.

18 = 2 × 32

27 = 33

45 = 32 × 5

Prime182745Lowest power
22———
332333232
5——5—

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

GCF = 32 = 9

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GCF Table

1st2nd3rdGCF
1827303
1827311
1827321
1827333
1827341
1827351
1827369
1827371
1827381
1827393
1827401
1827411
1827423
1827431
1827441
1827459
1827461
1827471
1827483
1827491
1827501
1827513
1827521
1827531
1827549
1827551
1827561
1827573
1827581
1827591

FAQ

What's the Greatest Common Factor (GCF) of 18, 27 and 45?

GCF of 18, 27 and 45 is 9

What prime factors do 18, 27 and 45 share?

All three factorizations contain 3 × 3, and multiplying those shared primes gives 9 — exactly the greatest common factor.

Can you get the GCF of 18, 27 and 45 two numbers at a time?

Yes. The GCF of 18 and 27 is 9, and the GCF of 9 and 45 is 9 — 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 : 27 : 45?

Divide every term by the GCF 9: 18 ÷ 9 = 2, 27 ÷ 9 = 3 and 45 ÷ 9 = 5. So 18 : 27 : 45 in lowest terms is 2 : 3 : 5, and no whole number other than 1 divides all three of those.

See Also