What is the Greatest Common Factor of 1991 and 1999?

Greatest common factor (GCF) of 1991 and 1999 is 1.

GCF(1991,1999) = 1

We will now calculate the prime factors of 1991 and 1999, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 1991 and 1999.

How to find the GCF of 1991 and 1999?

We will first find the prime factorization of 1991 and 1999. After we will calculate the factors of 1991 and 1999 and find the biggest common factor number .

Step-1: Prime Factorization of 1991

Prime factors of 1991 are 11, 181. Prime factorization of 1991 in exponential form is:

1991 = 11¹ × 181¹

Step-2: Prime Factorization of 1999

Prime factors of 1999 are 1999. Prime factorization of 1999 in exponential form is:

1999 = 1999¹

Step-3: Factors of 1991

List of positive integer factors of 1991 that divides 1991 without a remainder.

1, 11, 181

Step-4: Factors of 1999

List of positive integer factors of 1999 that divides 1991 without a remainder.

Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 1991 and 1999. The biggest common factor number is the GCF number.
So the greatest common factor 1991 and 1999 is 1.

Also check out the Least Common Multiple of 1991 and 1999