What is the Greatest Common Factor of 640 and 645?

Greatest common factor (GCF) of 640 and 645 is 5.

GCF(640,645) = 5

We will now calculate the prime factors of 640 and 645, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 640 and 645.

How to find the GCF of 640 and 645?

We will first find the prime factorization of 640 and 645. After we will calculate the factors of 640 and 645 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 645

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

645 = 3¹ × 5¹ × 43¹

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 645

List of positive integer factors of 645 that divides 640 without a remainder.

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

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 640 and 645. The biggest common factor number is the GCF number.
So the greatest common factor 640 and 645 is 5.

Also check out the Least Common Multiple of 640 and 645