GCF for 9, 12 and 18

"Greatest Common Factor of 3 Numbers" Calculator
Greatest Common Factor of
,
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What's the Greatest Common Factor (GCF) of 9, 12 and 18?

Answer

GCF of 9, 12 and 18 is
3

Common factors: 1, 3

3 divides all three: 9 ÷ 3 = 3, 12 ÷ 3 = 4, 18 ÷ 3 = 6 — and 3, 4 and 6 have no factor but 1 common to all of them, so no larger number divides all three.

9 = 32

12 = 22 × 3

18 = 2 × 32

Prime91218Lowest power
2—222—
3323323

— = 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
39123
49121
59121
69123
79121
89121
99123
910121
911121
912123
912131
912141
912153
912161
912171
912183
912191
912201
912213
912221
912231
912243
912251
912261
912273
912281
912291
912303
912311
912321

FAQ

What's the Greatest Common Factor (GCF) of 9, 12 and 18?

GCF of 9, 12 and 18 is 3

What prime factors do 9, 12 and 18 share?

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

Can you get the GCF of 9, 12 and 18 two numbers at a time?

Yes. The GCF of 9 and 12 is 3, and the GCF of 3 and 18 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 9 : 12 : 18?

Divide every term by the GCF 3: 9 ÷ 3 = 3, 12 ÷ 3 = 4 and 18 ÷ 3 = 6. So 9 : 12 : 18 in lowest terms is 3 : 4 : 6, and no whole number other than 1 divides all three of those.

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