What is the Greatest Common Factor of 680 and 685?

Greatest common factor (GCF) of 680 and 685 is 5.

GCF(680,685) = 5

We will now calculate the prime factors of 680 and 685, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 680 and 685.

How to find the GCF of 680 and 685?

We will first find the prime factorization of 680 and 685. After we will calculate the factors of 680 and 685 and find the biggest common factor number .

Step-1: Prime Factorization of 680

Prime factors of 680 are 2, 5, 17. Prime factorization of 680 in exponential form is:

680 = 2³ × 5¹ × 17¹

Step-2: Prime Factorization of 685

Prime factors of 685 are 5, 137. Prime factorization of 685 in exponential form is:

685 = 5¹ × 137¹

Step-3: Factors of 680

List of positive integer factors of 680 that divides 680 without a remainder.

1, 2, 4, 5, 8, 10, 17, 20, 34, 40, 68, 85, 136, 170, 340

Step-4: Factors of 685

List of positive integer factors of 685 that divides 680 without a remainder.

1, 5, 137

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 680 and 685. The biggest common factor number is the GCF number.
So the greatest common factor 680 and 685 is 5.

Also check out the Least Common Multiple of 680 and 685