What is the Greatest Common Factor of 645 and 655?

Greatest common factor (GCF) of 645 and 655 is 5.

GCF(645,655) = 5

We will now calculate the prime factors of 645 and 655, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 645 and 655.

How to find the GCF of 645 and 655?

We will first find the prime factorization of 645 and 655. After we will calculate the factors of 645 and 655 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 655

Prime factors of 655 are 5, 131. Prime factorization of 655 in exponential form is:

655 = 5¹ × 131¹

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 655

List of positive integer factors of 655 that divides 645 without a remainder.

1, 5, 131

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 645 and 655. The biggest common factor number is the GCF number.
So the greatest common factor 645 and 655 is 5.

Also check out the Least Common Multiple of 645 and 655