What is the Greatest Common Factor of 643 and 655?

Greatest common factor (GCF) of 643 and 655 is 1.

GCF(643,655) = 1

We will now calculate the prime factors of 643 and 655, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 643 and 655.

How to find the GCF of 643 and 655?

We will first find the prime factorization of 643 and 655. After we will calculate the factors of 643 and 655 and find the biggest common factor number .

Step-1: Prime Factorization of 643

Prime factors of 643 are 643. Prime factorization of 643 in exponential form is:

643 = 643¹

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 643

List of positive integer factors of 643 that divides 643 without a remainder.

Step-4: Factors of 655

List of positive integer factors of 655 that divides 643 without a remainder.

1, 5, 131

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 643 and 655. The biggest common factor number is the GCF number.
So the greatest common factor 643 and 655 is 1.

Also check out the Least Common Multiple of 643 and 655