What is the Greatest Common Factor of 640 and 646?

Greatest common factor (GCF) of 640 and 646 is 2.

GCF(640,646) = 2

We will now calculate the prime factors of 640 and 646, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 640 and 646.

How to find the GCF of 640 and 646?

We will first find the prime factorization of 640 and 646. After we will calculate the factors of 640 and 646 and find the biggest common factor number .

Step-1: Prime Factorization of 640

Prime factors of 640 are 2, 5. Prime factorization of 640 in exponential form is:

640 = 2⁷ × 5¹

Step-2: Prime Factorization of 646

Prime factors of 646 are 2, 17, 19. Prime factorization of 646 in exponential form is:

646 = 2¹ × 17¹ × 19¹

Step-3: Factors of 640

List of positive integer factors of 640 that divides 640 without a remainder.

1, 2, 4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 128, 160, 320

Step-4: Factors of 646

List of positive integer factors of 646 that divides 640 without a remainder.

1, 2, 17, 19, 34, 38, 323

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 640 and 646. The biggest common factor number is the GCF number.
So the greatest common factor 640 and 646 is 2.

Also check out the Least Common Multiple of 640 and 646