GCF (HCF) of 18 and 20

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Greatest Common Factor of
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What is the Greatest Common Divisor of 18 and 20?

Answer

GCF (HCF) of 18 and 20 is
2

Common factors: 1, 2

2 divides both: 18 ÷ 2 = 9, 20 ÷ 2 = 10 — and 9 and 10 share no factor but 1, so no larger number divides both.

18 = 2 × 32

20 = 22 × 5

Prime1820Lowest power
22222
332——
5—5—

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

GCF = 2

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GCF Table

Number 1Number 2GCF
18126
18142
18153
18202
18213
18222
18231
18246
18251
18262
18279
18282
18291
18306
18311
18322
18333
18342
18351
183618
18371
18382
18393
18402
18426
18431
18459
18462
18486
18491

FAQ

What is the Greatest Common Divisor of 18 and 20?

GCF (HCF) of 18 and 20 is 2

How to find the GCF of 18 and 20?

You can find the GCF of 18 and 20 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 18 and 20 is 2.

What prime factors do 18 and 20 share?

The prime factorizations of 18 and 20 have 2 in common, and multiplying those shared primes gives 2 — exactly the greatest common factor.

How does the GCF reduce the fraction 18/20?

Divide the numerator and the denominator by the GCF 2: 18 ÷ 2 = 9 and 20 ÷ 2 = 10. So 18/20 in lowest terms is 9/10.

See Also