GCF for 6, 9 and 15

"Greatest Common Factor of 3 Numbers" Calculator
Greatest Common Factor of
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What's the Greatest Common Factor (GCF) of 6, 9 and 15?

Answer

GCF of 6, 9 and 15 is
3

Common factors: 1, 3

3 divides all three: 6 ÷ 3 = 2, 9 ÷ 3 = 3, 15 ÷ 3 = 5 — and 2, 3 and 5 have no factor but 1 common to all of them, so no larger number divides all three.

6 = 2 × 3

9 = 32

15 = 3 × 5

Prime6915Lowest power
22———
333233
5——5—

— = 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
1691
2691
3693
4691
5691
6693
6791
6891
6993
69101
69111
69123
69131
69141
69153
69161
69171
69183
69191
69201
69213
69221
69231
69243
69251
69261
69273
69281
69291
69303

FAQ

What's the Greatest Common Factor (GCF) of 6, 9 and 15?

GCF of 6, 9 and 15 is 3

What prime factors do 6, 9 and 15 share?

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

Can you get the GCF of 6, 9 and 15 two numbers at a time?

Yes. The GCF of 6 and 9 is 3, and the GCF of 3 and 15 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 6 : 9 : 15?

Divide every term by the GCF 3: 6 ÷ 3 = 2, 9 ÷ 3 = 3 and 15 ÷ 3 = 5. So 6 : 9 : 15 in lowest terms is 2 : 3 : 5, and no whole number other than 1 divides all three of those.

See Also