What is the Greatest Common Factor of 390 and 399?

Greatest common factor (GCF) of 390 and 399 is 3.

GCF(390,399) = 3

We will now calculate the prime factors of 390 and 399, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 390 and 399.

How to find the GCF of 390 and 399?

We will first find the prime factorization of 390 and 399. After we will calculate the factors of 390 and 399 and find the biggest common factor number .

Step-1: Prime Factorization of 390

Prime factors of 390 are 2, 3, 5, 13. Prime factorization of 390 in exponential form is:

390 = 2¹ × 3¹ × 5¹ × 13¹

Step-2: Prime Factorization of 399

Prime factors of 399 are 3, 7, 19. Prime factorization of 399 in exponential form is:

399 = 3¹ × 7¹ × 19¹

Step-3: Factors of 390

List of positive integer factors of 390 that divides 390 without a remainder.

1, 2, 3, 5, 6, 10, 13, 15, 26, 30, 39, 65, 78, 130, 195

Step-4: Factors of 399

List of positive integer factors of 399 that divides 390 without a remainder.

1, 3, 7, 19, 21, 57, 133

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 390 and 399. The biggest common factor number is the GCF number.
So the greatest common factor 390 and 399 is 3.

Also check out the Least Common Multiple of 390 and 399