GCF for 3, 5 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 3, 5 and 15?

Answer

GCF of 3, 5 and 15 is
1

Common factors: 1

Only 1 divides all three: no prime is a factor of each of 3, 5 and 15.

Pairs do share factors — GCF(3, 15) = 3, GCF(5, 15) = 5 — just none greater than 1 common to all three.

3 — prime

5 — prime

15 = 3 × 5

Prime3515Lowest power
33—3—
5—55—

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

GCF = 1

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GCF Table

1st2nd3rdGCF
1351
2351
3351
3451
3551
3561
3571
3581
3591
35101
35111
35121
35131
35141
35151
35161
35171
35181
35191
35201
35211
35221
35231
35241
35251
35261
35271
35281
35291
35301

FAQ

What's the Greatest Common Factor (GCF) of 3, 5 and 15?

GCF of 3, 5 and 15 is 1

What prime factors do 3, 5 and 15 share?

None at all: 3, 5 and 15 have no prime factor in common, so the only positive integer dividing all three is 1 and their GCF is 1.

Can you get the GCF of 3, 5 and 15 two numbers at a time?

Yes. The GCF of 3 and 5 is 1, and the GCF of 1 and 15 is 1 — 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 3 : 5 : 15?

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

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