What is the greatest common factor of 18 and 51?

The greatest common factor of 18 and 51 is 3.

18 ÷ 3 = 6

51 ÷ 3 = 17

Method: One way to determine the greatest common factor is to find all the factors of the numbers and compare them.

The factors of 18 are 1, 2, 3, 6, 9, and 18.

The factors of 51 are 1, 3, 17, and 51.

The common factors are 1 and 3. Therefore, the greatest common factor is 3.

The greatest common factor can also be calculated by identifying the common prime factors and multiplying them together.

The prime factors of 18 are 2, 3, and 3.

The prime factors of 51 are 3 and 17.

The prime factors in common are a single 3, so the greatest common factor is 3.

The greatest common factor of 51 and 18 is 3