How do you find the Least Common Multiple (LCM)

of two or more numbers?

For example, how do you find the Least Common Multiple of 12 and 15?

In this lesson you will learn how to find the Least

Common Multiple of two or more numbers by creating

and comparing a list of multiples for each.

Let’s Review

A multiple is a product of two factors.

5 x 9 = 45

45 is a multiple of 9 and 5.

Let’s Review

Multiples are the result of skip counting.

Multiples of 5 are 5, 10, 15, 20, 25…

A Common Misunderstanding

Confusing multiples with factors

Find the multiples of 25.

1, 5, 25

Core Lesson

Multiples of 12

12 x 1 = 12 12 x 2 = 2412 x 3 = 3612 x 4 = 4812 x 5 = 60

{12, 24, 36, 48, 60}.

The set of the first five multiples of 12 is

Create a list of multiples for each number.

How do you find the Least Common Multiple (LCM) of

12 and 15?

Core Lesson

Multiples of 15

15 x 1 = 15 15 x 2 = 3015 x 3 = 4515 x 4 = 6015 x 5 = 75

{15, 30, 45, 60, 75}.

The set of the first five multiples of 15 is

Create a list of multiples for each number.

Core Lesson

{12, 24, 36, 48, 60}.The set of the first five

multiples of 12 is

{15, 30, 45, 60, 75}.The set of the first five

multiples of 15 is

The Least Common Multiple of 12 and 15 is 60.

Core Lesson How do you find the Least Common Multiple (LCM) of 4,

7 and 12?Multiples of 12 of 4? of 7? 12 x 1 = 12 yes no12 x 2 = 24 yes no12 x 3 = 36 yes no12 x 4 = 48 yes no12 x 5 = 60 yes no12 x 6 = 72 yes no12 x 7 = 84 yes yes

The LCM of 4, 7 and 12 is

84.

In this lesson you have learned to find the Least Common

Multiple of two or more numbers by creating and

comparing a list of multiples for each.