GCF (HCF) of 20 and 155

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Greatest Common Factor of
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What is the Greatest Common Divisor of 20 and 155?

Answer

GCF (HCF) of 20 and 155 is
5

Common factors: 1, 5

5 divides both: 20 ÷ 5 = 4, 155 ÷ 5 = 31 — and 4 and 31 share no factor but 1, so no larger number divides both.

20 = 22 × 5

155 = 5 × 31

Prime20155Lowest power
222——
5555
31—31—

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

GCF = 5

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GCF Table

Number 1Number 2GCF
20444
20455
20471
20484
205010
20555
20564
20582
20591
206020
207010
20755
20844
209010
2010020
201555
201655
2019010
202055
2023010
202355
2025010
203055
203855
2043010
2045010
2046020
204655
2047010
2048020

FAQ

What is the Greatest Common Divisor of 20 and 155?

GCF (HCF) of 20 and 155 is 5

How to find the GCF of 20 and 155?

You can find the GCF of 20 and 155 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 20 and 155 is 5.

What prime factors do 20 and 155 share?

The prime factorizations of 20 and 155 have 5 in common, and multiplying those shared primes gives 5 — exactly the greatest common factor.

How does the GCF reduce the fraction 20/155?

Divide the numerator and the denominator by the GCF 5: 20 ÷ 5 = 4 and 155 ÷ 5 = 31. So 20/155 in lowest terms is 4/31.

See Also