What is the Greatest Common Factor of 821 and 840?

Greatest common factor (GCF) of 821 and 840 is 1.

GCF(821,840) = 1

We will now calculate the prime factors of 821 and 840, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 821 and 840.

How to find the GCF of 821 and 840?

We will first find the prime factorization of 821 and 840. After we will calculate the factors of 821 and 840 and find the biggest common factor number .

Step-1: Prime Factorization of 821

Prime factors of 821 are 821. Prime factorization of 821 in exponential form is:

821 = 821¹

Step-2: 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-3: Factors of 821

List of positive integer factors of 821 that divides 821 without a remainder.

Step-4: Factors of 840

List of positive integer factors of 840 that divides 821 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

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 821 and 840. The biggest common factor number is the GCF number.
So the greatest common factor 821 and 840 is 1.

Also check out the Least Common Multiple of 821 and 840