GCF for 15 and 18

"Greatest Common Factor" Calculator

Greatest Common Factor of

and

What is the Greatest common Divisor of 15 and 18?

Answer: GCF of 15 and 18 is 3

(Three)

Finding GCF for 15 and 18 using all factors (divisors) listing

The first method to find GCF for numbers 15 and 18 is to list all factors for both numbers and pick the highest common one:

All factors of 15: 1, 3, 5, 15

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

So the Greatest Common Factor for 15 and 18 is 3

Finding GCF for 15 and 18 by Prime Factorization

The second method to find GCF for numbers 15 and 18 is to list all Prime Factors for both numbers and multiply the common ones:

All Prime Factors of 15: 3, 5

All Prime Factors of 18: 2, 3, 3

As we can see there is only one Prime Factor common to both numbers. It is 3

So 3 is the Greatest Common Factor of 15 and 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 15 and 18? (The answer is: 3). Select the first number (e.g. '15') and the second number (e.g. '18'). 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
1181
2182
3183
4182
5181
6186
7181
8182
9189
10182
11181
12186
13181
14182
15183
16182
17181
181818
19181
20182
21183
22182
23181
24186
25181
26182
27189
28182
29181
30186

FAQ

What is the Greatest common Divisor of 15 and 18?

GCF of 15 and 18 is 3

See Also