What is the Greatest Common Factor of 840 and 856?

Greatest common factor (GCF) of 840 and 856 is 8.

GCF(840,856) = 8

We will now calculate the prime factors of 840 and 856, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 840 and 856.

How to find the GCF of 840 and 856?

We will first find the prime factorization of 840 and 856. After we will calculate the factors of 840 and 856 and find the biggest common factor number .

Step-1: Prime Factorization of 840

Prime factors of 840 are 2, 3, 5, 7. Prime factorization of 840 in exponential form is:

840 = 2³ × 3¹ × 5¹ × 7¹

Step-2: Prime Factorization of 856

Prime factors of 856 are 2, 107. Prime factorization of 856 in exponential form is:

856 = 2³ × 107¹

Step-3: Factors of 840

List of positive integer factors of 840 that divides 840 without a remainder.

1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 15, 20, 21, 24, 28, 30, 35, 40, 42, 56, 60, 70, 84, 105, 120, 140, 168, 210, 280, 420

Step-4: Factors of 856

List of positive integer factors of 856 that divides 840 without a remainder.

1, 2, 4, 8, 107, 214, 428

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 840 and 856. The biggest common factor number is the GCF number.
So the greatest common factor 840 and 856 is 8.

Also check out the Least Common Multiple of 840 and 856