### Home > CC1 > Chapter 3 > Lesson 3.2.4 > Problem 3-130

3-130.

Find the greatest common factor and the least common multiple of each of the following sets of numbers.

12 and 7

7 is a prime number, so its only factor other than itself is 1.

Their greatest common factor is 1. Can you find their least common multiple?

3, 15, and 9

To find the least common multiple, try finding multiples of 15 and checking

whether they are also multiples of 3 and 9.The least common multiple is 45. Try finding the greatest common factor.

20 and 30

10 is a factor of both of these numbers.