# Greatest Common Factor of 15 and 20

Make use of GCF Calculator to quickly find the Greatest Common Factor of numbers 15, 20 i.e. 5 largest integer by which both the numbers can be divided.

Greatest common factor (GCF) of 15 and 20 is 5.

GCF(15,20) = 5

## GCF of 15 and 20

Greatest common factor or Greatest common divisor (GCD) can be calculated in following way;

GCF of:
and

### Greatest Common Factor of 15 and 20 by Prime factorization method

Prime Factorization of 15

 3 15 5 5 1

Prime factors of 15 are 3,5. Prime factorization of 15 in exponential form is:

15 = 31×51

Prime Factorization of 20

 2 20 2 10 5 5 1

Prime factors of 20 are 2,5. Prime factorization of 20 in exponential form is:

20 = 22×51

∴ So by taking common prime factors GCF of 15 and 20 is 5

### Greatest Common Factor of 15 and 20 by matching factors method

Factors of 15

List of positive integer factors of 15 that divides 15 without a remainder.

1,3,5,15

Factors of 20

List of positive integer factors of 20 that divides 20 without a remainder.

1,2,4,5,10,20

Greatest Common Factor

We found the factors and prime factorization of 15 and 20. The biggest common factor number is the GCF number.
So the greatest common factor 15 and 20 is 5.

Also check out the Least Common Multiple of 15 and 20

### Properties of GCF 15 and 20

(i) The GCF of 15 and 20 is associative

GCF of 15 and 20 = GCF of 20 and 15

### Frequently Asked Questions on GCF of 15 and 20

1. What is the GCF of 15 and 20?

Answer: GCF of 15 and 20 is 5.

2. What are the Factors of 15?

Answer: Factors of 15 are 1, 3, 5, 15. There are 4 integers that are factors of 15. The greatest factor of 15 is 15.

3. What are the Factors of 20?

Answer: Factors of 20 are 1, 2, 4, 5, 10, 20. There are 6 integers that are factors of 20. The greatest factor of 20 is 20.

4. How to Find the GCF of 15 and 20?

Greatest Common Factor of 15 and 20 = 5

Step 1: Find the prime factorization of 15

15 = 3 x 5

Step 2: Find the prime factorization of 20

20 = 2 x 2 x 5

Step 3: Multiply those factors both numbers have in common in steps i) or ii) above to find the gcf:

GCF = 5

Step 4: Therefore, the greatest common factor of 15 and 20 is 5