What is the greatest common factor of 15 and 20?

Answer 1

The GCF of 15 and 20 is 5.

Since 15 = 3x5 and 20 = 2 x 2 x 5, the greatest common factor is 5.

One way to approach this is to look at the difference between 15 and 20, which is 5. The greatest common factor of two numbers cannot be larger than the difference between the two numbers. Since both 15 and 20 are divisible by 5, the greatest common factor is 5.

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

The factors of 15 are 1, 3, 5, and 15.

The factors of 20 are 1, 2, 4, 5, 10, and 20.

The common factors are 1 and 5. Therefore, the greatest common factor is 5.

The GCF is 5.

Divide each number by prime numbers until it you get to 1.

For example, 15 --> 5(3)

20 --> 2(10) --> 2(2)(5)

Compare the end results for both numbers, find the ones they have in common and multiply them together to get the gcf. In this case, it would only be 5.
The GCF is 5.

Answer 2

15 = 3 x 5

20 = 2 x 2 x 5

The GCF of 20 and 15 is 5.

Answer 3

The GCF is 5.

Answer 4

The answer is 5.