What is the Greatest Common Factor of 645 and 651?

Greatest common factor (GCF) of 645 and 651 is 3.

GCF(645,651) = 3

We will now calculate the prime factors of 645 and 651, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 645 and 651.

How to find the GCF of 645 and 651?

We will first find the prime factorization of 645 and 651. After we will calculate the factors of 645 and 651 and find the biggest common factor number .

Step-1: Prime Factorization of 645

Prime factors of 645 are 3, 5, 43. Prime factorization of 645 in exponential form is:

645 = 3¹ × 5¹ × 43¹

Step-2: Prime Factorization of 651

Prime factors of 651 are 3, 7, 31. Prime factorization of 651 in exponential form is:

651 = 3¹ × 7¹ × 31¹

Step-3: Factors of 645

List of positive integer factors of 645 that divides 645 without a remainder.

1, 3, 5, 15, 43, 129, 215

Step-4: Factors of 651

List of positive integer factors of 651 that divides 645 without a remainder.

1, 3, 7, 21, 31, 93, 217

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 645 and 651. The biggest common factor number is the GCF number.
So the greatest common factor 645 and 651 is 3.

Also check out the Least Common Multiple of 645 and 651