Finding the GCF - Ms. Arnold 6th Grade...
Transcript of Finding the GCF - Ms. Arnold 6th Grade...
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Finding the GCF
I can find the GCF of two whole numbers less than or equal to
100.
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What is a GCF?
The Greatest Common Factor (G.C.F.) of two
numbers is the largest number that is a divisor
of both. It can be used to simplify (or reduce)
fractions.
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What is a GCF?
GREATEST is biggest or largest.
COMMON is something shared or in common.
FACTORS are the parts of multiplication facts.
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What is a GCF? There are multiple ways to
find the GCF
Today we will talk about two of the following two methods:
1) The Tree Method (Prime Factorization)
2) Listing Method
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Tree Method 1) Break the number down until
it is only prime numbers 2) List the number as a
factor of primes 3) Find all the prime numbers
the two original number share
4) Multiply. The product is the greatest common
factor
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Tree Method Break each number down to prime
factors. 56 84
2 28 2 14 2 7
42
2
2
7 6
3
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Prime Factorization of 56 and 84
56: 2x2x2x7 84: 2x2x7x3
Multiply only one row. 2x2x7
The GCF is 28
Circle what they have in
common
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Tree Method Break each number down to prime
factors. 63 81
7 9 3 3
9 9
3 3 3 3
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Prime Factorization of 63 and 81
63:3X3x7 81:3x3x3x3
Multiply only one row. 3x3
The GCF is 9
Circle what they have in
common
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Tree Method
48 56
6 8
4 2 3 2
2 2
8 7
4 2
2 2
48 : 2 x 2 x 2 x 2 x 3 56: 2 x 2 x 2 x 7
2 x 2 x 2 = 6 GCF = 6
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Tree Method
24 36
6 3
3 2
9
3 3 2 2
24 : 2 x 3 x 3 36 : 2 x 2 x 3 x 3 2 x 3= 6
GCF = 6
4
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Now try example 5 through 8 using the
tree method by yourself!
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Exit
Sli
p
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Finding the GCF Activity
I can find the GCF of two whole numbers less than or equal to
100.
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Find the GCF of the following numbers
26 and 42
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Find the GCF of the following numbers
30 and 40
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Find the GCF of the following numbers
32 and 44
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Find the GCF of the following numbers
27 and 45
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Find the GCF of the following numbers
36 and 48
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Find the GCF of the following numbers
65 and 91
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Find the GCF of the following numbers
84 and 92
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Find the GCF of the following numbers
51 and 75
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Find the GCF of the following numbers
64 and 72
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Find the GCF of the following numbers
99 and 66
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Find the GCF of the following numbers
20 and 24
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Find the GCF of the following numbers
21 and 56
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Find the GCF of the following numbers
18 and 90
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Find the GCF of the following numbers
8 and 64
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Find the GCF of the following numbers
20 and 45
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Find the GCF of the following numbers
18 and 63
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Find the GCF of the following numbers
42 and 48
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Find the GCF of the following numbers
16 and 28
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Find the GCF of the following numbers
30 and 42
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Find the GCF of the following numbers
36 and 72
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Find the GCF of the following numbers
15 and 40
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Find the GCF of the following numbers
24 and 28
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Find the GCF of the following numbers
24 and 32
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Find the GCF of the following numbers
9 and 54
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Find the GCF of the following numbers
40 and 50
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Find the GCF of the following numbers
6 and 36