How do you get the GCF of 15 and 30?

Answer 1

-- List all the factors of 15.

-- List all the factors of 30.

-- Spot the group of numbers that are on both lists.

-- The biggest one of those is the GCF. It should be close to 15.

Answer 2

Since 15 is a factor of 30, it is automatically the GCF.

3 x 5 = 15

2 x 3 x 5 = 30

Select the common factors.

3 x 5 = 15, the GCF.