GCF (HCF) of 45 and 108

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What is the Greatest Common Divisor of 45 and 108?

Answer

GCF (HCF) of 45 and 108 is
9

Common factors: 1, 3, 9

9 divides both: 45 ÷ 9 = 5, 108 ÷ 9 = 12 — and 5 and 12 share no factor but 1, so no larger number divides both.

45 = 32 × 5

108 = 22 × 33

Prime45108Lowest power
2—22—
3323332
55——

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

GCF = 32 = 9

See Also

FAQ

What is the Greatest Common Divisor of 45 and 108?

GCF (HCF) of 45 and 108 is 9

How to find the GCF of 45 and 108?

You can find the GCF of 45 and 108 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 45 and 108 is 9.

What prime factors do 45 and 108 share?

The prime factorizations of 45 and 108 have 3 × 3 in common, and multiplying those shared primes gives 9 — exactly the greatest common factor.

How does the GCF reduce the fraction 45/108?

Divide the numerator and the denominator by the GCF 9: 45 ÷ 9 = 5 and 108 ÷ 9 = 12. So 45/108 in lowest terms is 5/12.