What is the Greatest Common Factor of 9 and 15?

Greatest common factor (GCF) of 9 and 15 is 3.

GCF(9,15) = 3

We will now calculate the prime factors of 9 and 15, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 9 and 15.

How to find the GCF of 9 and 15?

We will first find the prime factorization of 9 and 15. After we will calculate the factors of 9 and 15 and find the biggest common factor number .

Step-1: Prime Factorization of 9

Prime factors of 9 are 3. Prime factorization of 9 in exponential form is:

9 = 3²

Step-2: Prime Factorization of 15

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

15 = 3¹ × 5¹

Step-3: Factors of 9

List of positive integer factors of 9 that divides 9 without a remainder.

1, 3

Step-4: Factors of 15

List of positive integer factors of 15 that divides 9 without a remainder.

1, 3, 5

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 9 and 15. The biggest common factor number is the GCF number.
So the greatest common factor 9 and 15 is 3.

Also check out the Least Common Multiple of 9 and 15