GCF (HCF) of 15 and 45

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What is the Greatest Common Divisor of 15 and 45?

Answer

GCF (HCF) of 15 and 45 is
15

Common factors: 1, 3, 5, 15

15 divides 45 (45 ÷ 15 = 3), so the GCF is the smaller number itself.

15 = 3 × 5

45 = 32 × 5

Prime1545Lowest power
33323
5555

GCF = 3 × 5 = 15

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GCF Table

Number 1Number 2GCF
15243
15255
15261
15273
15281
15291
153015
15321
15333
15355
15363
15381
15405
15423
15441
154515
15483
15491
15505
15531
15543
15555
15561
156015
15641
157515
15771
15805
151005
151255

FAQ

What is the Greatest Common Divisor of 15 and 45?

GCF (HCF) of 15 and 45 is 15

How to find the GCF of 15 and 45?

You can find the GCF of 15 and 45 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 15 and 45 is 15.

What prime factors do 15 and 45 share?

The prime factorizations of 15 and 45 have 3 × 5 in common, and multiplying those shared primes gives 15 — exactly the greatest common factor.

How does the GCF reduce the fraction 15/45?

Divide the numerator and the denominator by the GCF 15: 15 ÷ 15 = 1 and 45 ÷ 15 = 3. So 15/45 in lowest terms is 1/3.

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