What is the Greatest Common Factor of 1220 and 1240?

Greatest common factor (GCF) of 1220 and 1240 is 20.

GCF(1220,1240) = 20

We will now calculate the prime factors of 1220 and 1240, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 1220 and 1240.

How to find the GCF of 1220 and 1240?

We will first find the prime factorization of 1220 and 1240. After we will calculate the factors of 1220 and 1240 and find the biggest common factor number .

Step-1: Prime Factorization of 1220

Prime factors of 1220 are 2, 5, 61. Prime factorization of 1220 in exponential form is:

1220 = 2² × 5¹ × 61¹

Step-2: Prime Factorization of 1240

Prime factors of 1240 are 2, 5, 31. Prime factorization of 1240 in exponential form is:

1240 = 2³ × 5¹ × 31¹

Step-3: Factors of 1220

List of positive integer factors of 1220 that divides 1220 without a remainder.

1, 2, 4, 5, 10, 20, 61, 122, 244, 305, 610

Step-4: Factors of 1240

List of positive integer factors of 1240 that divides 1220 without a remainder.

1, 2, 4, 5, 8, 10, 20, 31, 40, 62, 124, 155, 248, 310, 620

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 1220 and 1240. The biggest common factor number is the GCF number.
So the greatest common factor 1220 and 1240 is 20.

Also check out the Least Common Multiple of 1220 and 1240