GCF (HCF) of 18 and 66

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What is the Greatest Common Divisor of 18 and 66?

Answer

GCF (HCF) of 18 and 66 is
6

Common factors: 1, 2, 3, 6

6 divides both: 18 ÷ 6 = 3, 66 ÷ 6 = 11 — and 3 and 11 share no factor but 1, so no larger number divides both.

18 = 2 × 32

66 = 2 × 3 × 11

Prime1866Lowest power
2222
33233
11—11—

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

GCF = 2 × 3 = 6

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GCF Table

Number 1Number 2GCF
18426
18431
18459
18462
18486
18491
18502
185418
18551
18562
18582
18591
18606
18639
18642
18666
18702
187218
18753
18786
18802
18819
18846
18882
18966
18999
181002
1810818
181122
181206

FAQ

What is the Greatest Common Divisor of 18 and 66?

GCF (HCF) of 18 and 66 is 6

How to find the GCF of 18 and 66?

You can find the GCF of 18 and 66 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 18 and 66 is 6.

What prime factors do 18 and 66 share?

The prime factorizations of 18 and 66 have 2 × 3 in common, and multiplying those shared primes gives 6 — exactly the greatest common factor.

How does the GCF reduce the fraction 18/66?

Divide the numerator and the denominator by the GCF 6: 18 ÷ 6 = 3 and 66 ÷ 6 = 11. So 18/66 in lowest terms is 3/11.

See Also