Lesson 5-6 Pages 226-230

Least Common Multiple

Lesson Check 5-5

What you will learn!1. How to find the LCM of two

or more numbers.

2. How to find the LCD of two or more fractions.

MultipleMultiple

Common MultipleCommon Multiple

Least common multipleLeast common multiple

Least common denominatorLeast common denominator

What you really need to know!

The least common multiple (LCM) is the least nonzero number that is a multiple of the given numbers.

What you really need to know!

The least common denominator (LCD) of two or more fractions is the LCM of the denominators.

LCM = 2 2 2 3 3 = 72

8 = 2 2 2

18 = 2 3 3

Example:

Find the LCM of 8 and 18.8 88 1616 2424 3232 4040 4848 5656 6464 7272

18 1818 3636 5454 7272 9090 108108 126126 144144 162162

8 88 1616 2424 3232 4040 4848 5656 6464 7272

18 1818 3636 5454 7272 9090 108108 126126 144144 162162

Example 1:

Find the LCM of 24 and 18.

322224 33218

23 • 32 = 72

Example 2:

Find the LCM of 168 and 180.

73222168 53322180

23 • 32 • 5 • 7 = 2,520

Example 3:

Find the LCM of 12x2y2 and 6y3

yyxxyx 32212 22

yyyy 326 3

2•2•3•x•x•y•y•y=12x2y3

Example 4:

Find the LCD of 7/8 and 13/20 :

2228 52220

2•2•2•5=40

Example 5:

Find the LCD of 9/36a2b and 16/27ab2 :

baaba 332236 2

bbaab 33327 2

2•2•3•3•3•a•a•b•b = 108a2b2

Example 6:

7

3?

15

7

105

49

7

7

15

7

105

45

15

15

7

3

7

3

15

7

Replace the ? with <, >, or =.

Page 228

Guided Practice

#’s 3-15

Pages 226-228 with someone at home and study

examples!

Read:

Homework: Pages 229-230

#’s 16-54 even

#’s 61-80

Lesson Check 5-6

Page

735

Lesson 5-6

Lesson Check 5-6