GCF of 18 and 108 (Greatest Common Factor)

"Greatest Common Factor" Calculator
Greatest Common Factor of
and

What is the Greatest Common Divisor of 18 and 108?

Answer

GCF of 18 and 108 is
18

(Eighteen)

Finding GCF for 18 and 108 using all factors (divisors) listing

The first method to find GCF for numbers 18 and 108 is to list all factors for both numbers and pick the highest common one:

All factors of 18: 1, 2, 3, 6, 9, 18

All factors of 108: 1, 2, 3, 4, 6, 9, 12, 18, 27, 36, 54, 108

So the Greatest Common Factor for 18 and 108 is 18

Finding GCF for 18 and 108 by Prime Factorization

The second method to find GCF for numbers 18 and 108 is to list all Prime Factors for both numbers and multiply the common ones:

All Prime Factors of 18: 2, 3, 3

All Prime Factors of 108: 2, 2, 3, 3, 3

As we can see there are Prime Factors common to both numbers: 2, 3, 3

Now we need to multiply them to find GCF: 2 × 3 × 3 = 18

Related Calculations

See Also

About "Greatest Common Factor" Calculator

This calculator will help you find the greatest common factor (GCF) of two numbers. For example, it can help you find out what is the Greatest Common Divisor of 18 and 108? (The answer is: 18). Select the first number (e.g. '18') and the second number (e.g. '108'). After that hit the 'Calculate' button.
Greatest Common Factor (GCF) also known as the Greatest Common Divisor (GCD) or Highest Common Factor (HCF) - it is the largest positive integer that divides each of the integers with zero remainder.
"Greatest Common Factor" Calculator
Greatest Common Factor of
and

GCF Table

Number 1Number 2GCF
18502
18513
185418
18551
18562
18573
18582
18591
18606
18639
18642
18666
18702
187218
18753
18786
18802
18819
18846
18882
189018
18966
18999
181002
1810818
181122
181206
181302
182259
182502

FAQ

What is the Greatest Common Divisor of 18 and 108?

GCF of 18 and 108 is 18

How to find the GCF of 18 and 108?

You can find the GCF of 18 and 108 by listing all factors of both numbers and picking the greatest common one, or by prime factorization. The GCF of 18 and 108 is 18.

What prime factors do 18 and 108 share?

The prime factorizations of 18 and 108 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 18/108?

Divide the numerator and the denominator by the GCF 18: 18 ÷ 18 = 1 and 108 ÷ 18 = 6. So 18/108 in lowest terms is 1/6.

See Also