GCF (HCF) of 18 and 31

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Greatest Common Factor of
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What is the Greatest Common Divisor of 18 and 31?

Answer

GCF (HCF) of 18 and 31 is
1

Common factors: 1

Only 1 divides both: 18 and 31 share no prime factor.

Such numbers are called coprime (relatively prime); their LCM is just the product: 18 × 31 = 558.

18 = 2 × 32

31 — prime

Prime1831Lowest power
22——
332——
31—31—

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

GCF = 1

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GCF Table

Number 1Number 2GCF
18126
18142
18153
18202
18213
18222
18231
18246
18251
18262
18279
18282
18306
18311
18322
18333
18342
18351
183618
18371
18382
18393
18402
18426
18431
18459
18462
18471
18486
18491

FAQ

What is the Greatest Common Divisor of 18 and 31?

GCF (HCF) of 18 and 31 is 1

How to find the GCF of 18 and 31?

You can find the GCF of 18 and 31 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 18 and 31 is 1.

What prime factors do 18 and 31 share?

18 and 31 have no prime factor in common, so the only integer that divides both of them is 1 and their GCF is 1.

How does the GCF reduce the fraction 18/31?

Divide the numerator and the denominator by the GCF 1: 18 ÷ 1 = 18 and 31 ÷ 1 = 31. So 18/31 in lowest terms is 18/31.

Are 18 and 31 coprime?

Yes, 18 and 31 are coprime (relatively prime) because their Greatest Common Factor is 1.

See Also