What is the greatest common factor of 51 and 20?

Answer 1

Greatest common factor of 20 & 51 is 1.

Factors of 20 are 1, 2, 4, 5, 10 & 20.

Factors of 51 are 1, 3, 17 & 51.

The only common factor is 1, so GCF is 1.

Alternate method:

Prime factorization of 20 = 2x2x5

Prime factorization of 51 = 3x17

From the prime factorizations it is clear that 1 is the GCF of 20 and 51.

Answer 2

The GCF of 20 and 51 is 1.

Answer 3

The greatest common factor of 51 , 20 = 1