GCF (HCF) of 18 and 72

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What is the Greatest Common Divisor of 18 and 72?

Answer

GCF (HCF) of 18 and 72 is
18

Common factors: 1, 2, 3, 6, 9, 18

18 divides 72 (72 ÷ 18 = 4), so the GCF is the smaller number itself.

18 = 2 × 32

72 = 23 × 32

Prime1872Lowest power
22232
3323232

GCF = 2 × 32 = 18

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GCF Table

Number 1Number 2GCF
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
181302
182259

FAQ

What is the Greatest Common Divisor of 18 and 72?

GCF (HCF) of 18 and 72 is 18

How to find the GCF of 18 and 72?

You can find the GCF of 18 and 72 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 18 and 72 is 18.

What prime factors do 18 and 72 share?

The prime factorizations of 18 and 72 have 2 × 3 × 3 in common, and multiplying those shared primes gives 18 — exactly the greatest common factor.

How does the GCF reduce the fraction 18/72?

Divide the numerator and the denominator by the GCF 18: 18 ÷ 18 = 1 and 72 ÷ 18 = 4. So 18/72 in lowest terms is 1/4.

See Also