Download Objective B- Find the LCM by Prime Factorization Method

Basic Math MA 050
Objective A. Find Common Multiples
and LCM
1. List the first 8 multiples of each number.
5: ____, ____, ____, ____, ____, ____, ____, ____
4: ____, ____, ____, ____, ____, ____, ____, ____
Section 3,2 Least Common Multiple
Student Practice
1.b List the first 8 multiples of each
number.
9: ____, ____, ____, ____, ____, ____, ____, ____
5: ____, ____, ____, ____, ____, ____, ____, ____
Which multiples listed above are common to both
numbers? (Called COMMON MULTIPLES)
__________
__________
Which multiples listed above are common to both
numbers? (Called COMMON MULTIPLES)
__________
__________
What is the LEAST (smallest) COMMON MULTIPLE
(LCM)?
____________ (Complete problem at right →)
What is the LEAST (smallest) COMMON MULTIPLE
(LCM)?
__________ is LCM for 9 and 5
A different method to find LCM
2. Find the LCM for 9 and 12
2.b Find the LCM for 9 and 15
First, list the multiples of the largest number until a
number that is a multiple of the smaller number
appears:
First, list the multiples of the largest number until a
number that is a multiple of the smaller number
appears:
Solution
12 · 1 = 12 (not a multiple of 9)
12 · 2 = 24 (not a multiple of 9)
12 · 3 = 36 (A multiple of 9)
Solution
15 · 1 = 15
15 · 2 = _____
______________
The LCM of 9 and 15 is ________
The LCM of 9 and 12 is ________
(Complete problems at right →)
2.C Find LCM of 8 and 16
Assignment: All Odd Numbered Problems , Pages 188-190 (1, 3, 5, 7, . . . )
Basic Math MA 050
Section 3,2 Least Common Multiple
Objective B- Find the LCM by Prime
Factorization Method
Student Practice
3. Find the LCM of 270 and 84 by Prime
Factorization Method.
3.b Find the LCM of 72 and 60 by Prime
Factorization Method.
1st : List the prime Factors for each number:
1st : List the prime Factors for each number:
(Do this by division process)
(Do this by division process)
270:
72:
84:
60:
2nd Circle the greatest number of primes in
each set.
2nd Circle the greatest number of primes in
each set.
3rd: Find the product of the circled primes:
3rd: Find the product of the circled primes:
The LCM is ____________
The LCM is ____________
More Practice: # 10, Page 188
Assignment: All Odd Numbered Problems , Pages 188-190 (1, 3, 5, 7, . . . )
Basic Math MA 050
Section 3,2 Least Common Multiple
More Practice Using Exponents
Student Practice
4. Find the LCM by prime factorization for
the numbers 120 and 108
4.b Find the LCM by prime factorization for
the numbers 216 and 180
1st : List the prime Factors for each number:
(Do this by division process)
1st : List the prime Factors for each number:
(Do this by division process)
216:
120:
List as exponents of the base prime
List as exponents of the base prime
180:
108:
List as exponents of the base prime
List as exponents of the base prime
2nd Circle the primes with largest exponent
in each set.
2nd Circle the primes with largest exponent
in each set.
3rd: Find the product of the circled primes:
3rd: Find the product of the circled primes:
The LCM in prime factored form is :
____________
The LCM in prime factored form is :
____________
Assignment: All Odd Numbered Problems , Pages 188-190 (1, 3, 5, 7, . . . )
Basic Math MA 050
Section 3,2 Least Common Multiple
Now Let’s Try Three Numbers
Student Practice
# 18, Page 188
#30, Page 188
Objective C: Writing Equivalent Fractions
Rewrite
1
3
as
?
Rewrite
12
Divide and multiply, like this:
Rewrite
1
3
=
4
12
7
8
as
?
56
Divide and multiply, like this:
Rewrite
7
8
Assignment: All Odd Numbered Problems , Pages 188-190 (1, 3, 5, 7, . . . )
=
56