gcf&lcm
TRANSCRIPT
PRIME FACTORIZATIONGCF & LCM
FACTORING
Factoring is the opposite of multiplying A Factor Times another Factor Equals a Product A Composite Number can be factored by two or more numbers Factoring is breaking Down a Product into it’s Factors Prime Factorization is breaking down a Product into it’s Prime Factors.
FACTOR TREE
A factor tree breaks a product down into it’s Prime Factors. It is called PRIME FACTORIZATION
30
3 10
3 • 2 • 5
PRODUCT
PRIME FACTORS
Prime Factorization
Factor 225
Prime Factorization
Factor 225
1. Put number on top of factor tree. 225
Prime Factorization
Factor 225
1. Put number on top of factor tree.
2. Find factors and branch down tree
225
5 45
5 9
5 • 5 • 3 • 3 = 32 • 52
GCF - Greatest Common Factor
The GCF of two numbers is the greatest number that divides into both numbers evenly.
Ex: The GCF of 14 & 35 is 7, since 7 is the greatest number that goes into both 14 & 35 evenly
HOW TO FIND THE GCF
The key to determining the GCF is to identify Common Factors in Both Numbers and Multiplying them together.
COMMON FACTORS OF 225 & 30
THE COMMON FACTORS ARE 5 & 3
225
5 45
5 9
5 • 5 • 3 • 3
3 10
30
3 • 5 • 2
IDENTIFY COMMON FACTORS
3 • 5 • 2 7 • 5 • 2 • 17
IDENTIFY COMMON FACTORS
THE COMMON FACTORS ARE 5 & 2
3 • 5 • 2 7 • 5 • 2 • 17
IDENTIFY COMMON FACTORS
7 • 5 • 5 • 3 • 3 2 • 5 • 2 • 5 • 7
IDENTIFY COMMON FACTORS
THE COMMON FACTORS ARE 7 & 5 & 5
7 • 5 • 5 • 3 • 3 2 • 5 • 2 • 5 • 7
IDENTIFY COMMON FACTORS
7 • 5 • 5 • 3 • 3 2 • 5 • 2 • 5 • 7&
2 • 11 • 5 • 3 • 7 13 • 3 • 2 • 5 • 2&
3 • 5 • 11 • 3 • 3 2 • 2 • 2 • 17 • 7&
5 • 5 • 7 • 3 2 • 5 • 2 • 3& 2 • 5 • 2 • 7&
For three numbers common factors must be in all three numbers
IDENTIFY COMMON FACTORS
7 • 5 • 5 • 3 • 3 2 • 5 • 2 • 5 • 7&
2 • 11 • 5 • 3 • 7 13 • 3 • 2 • 5 • 2&
3 • 5 • 11 • 3 • 3 2 • 2 • 2 • 17 • 7&
5 • 5 • 7 • 3 2 • 5 • 2 • 3& 2 • 5 • 2 • 7&
For three numbers common factors must be in all three numbers
5•5•7
2•5•3
None
Only 2 is in common
Finding Greatest Common FactorFind GCF of 225 & 30
Finding Greatest Common Factor
225
5 45
5 9
5 • 5 • 3 • 3
3 10
30
3 • 5 • 2
Find GCF of 225 & 30
1. Complete Factor Tree for both numbers.
Finding Greatest Common Factor
THE COMMON FACTORS ARE 5 & 3
225
5 45
5 9
5 • 5 • 3 • 3
3 10
30
3 • 5 • 2
Find GCF of 225 & 30
1. Complete Factor Tree for both numbers.
2. Identify Common Factors.
Finding Greatest Common Factor
THE COMMON FACTORS ARE 5 & 3
225
5 45
5 9
5 • 5 • 3 • 3
3 10
30
3 • 5 • 2
Find GCF of 225 & 30
1. Complete Factor Tree for both numbers.
2. Identify Common Factors.
3. Multiply Common Factors for GCF
GCF = 5 • 3 = 15
Finding the LCMLeast Common Multiple
The LCM is the Lowest Number that is a Multiple of Both Numbers.Ex. The LCM of 12 & 9 is 36 since both 12 & 9 divide evenly into 36.
Hint: Think of Common Denominators in Fractions.A common denominator is the LCM of the denominators.
€
1
6+
1
8=
4
24+
3
24=
7
24
Finding the LCMLeast Common Multiple
Finding Least Common MultipleFind LCM of 45 & 25
Finding Least Common Multiple
45
5 9
5 • 3 • 3 5 • 5 • 3
25 3
Find LCM of 45 & 25
1. Complete Factor Tree for both numbers.
75
Finding Least Common Multiple
THE COMMON FACTORS ARE 5 & 3
45
5 9
5 • 3 • 3 5 • 5 • 3
25 3
Find LCM of 45 & 25
1. Complete Factor Tree for both numbers.
2. Identify Common Factors.
75
Finding Least Common Multiple
THE COMMON FACTORS ARE 5 & 3
45
5 9
5 • 3 • 3 5 • 5 • 3
25 3
Find LCM of 45 & 25
1. Complete Factor Tree for both numbers.
2. Identify Common Factors.
3. Multiply Common Factors with ALL OTHER FACTORS
LCM = CF’s•ALL OTHER FACTORSLCM = 5•3 • 5 • 3 = 225
75
OTHER FACTORS
Finding Least Common MultipleFind LCM of 12 & 34
1. Complete Factor Tree for both numbers.
2. Identify Common Factors.
3. Multiply CF’s with ALL OTHER FACTORS
Find LCM of 225, 10 & 66
Finding the LCMLeast Common Multiple
(FOR 3 NUMBERS)
Find LCM of 225, 10 & 66
1. Complete Factor Tree for all numbers.
Finding the LCMLeast Common Multiple
(FOR 3 NUMBERS)225
5 45
5 9
5 • 5 • 3 • 3
11 6
66
11 • 3 • 2
5 • 2
10
Find LCM of 225, 10 & 66
1. Complete Factor Tree for all numbers.
2. Identify Common Factors OF ANY 2 #’S.
Finding the LCMLeast Common Multiple
(FOR 3 NUMBERS)
THE COMMON FACTORS ARE 2,5 & 3
225
5 45
5 9
5 • 5 • 3 • 3
11 6
66
11 • 3 • 2
5 • 2
10
Find LCM of 225, 10 & 66
1. Complete Factor Tree for all numbers.
2. Identify Common Factors OF ANY 2 #’S.
3. Multiply Common Factors with ALL OTHER FACTORS
OTHER FACTORS
Finding the LCMLeast Common Multiple
(FOR 3 NUMBERS)
THE COMMON FACTORS ARE 2,5 & 3
225
5 45
5 9
5 • 5 • 3 • 3
11 6
66
11 • 3 • 2
5 • 2
10
LCM=2•5•3•5•3•11=4950