Download Factors

Factors
􀀹 0506.2.2 Use the prime factorization
of two whole numbers to determine
the greatest common factor and the
least common multiple.
Factors
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Factor: Any one of the numbers
multiplied in a multiplication problem.
Factor: A whole number that divides
another whole number without a
remainder.
Prime Numbers
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A counting number greater than 1, whose
only two factors are the number 1 and itself.
Examples:
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2: 1x2
3: 1x3
5: 1x5
7: 1x7
11: 1x11
Composite Number
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A counting number greater than 1 that is
divisible by a number other than itself and 1.
Every composite number has at least three
factors.
Every composite number can be expressed as
a product of two or more prime numbers.
Examples:
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4: 1, 2, 4
6: 1, 2, 3, 6
Greatest Common Factor
(GCF)
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The largest whole number that is a factor of
two or more given numbers.
Example
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15: 1, 3, 5, 15
20: 1, 2, 4, 5, 10, 20
What factors do 15 and 20 have in common?
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1 and 5
Which one of the factors is greatest or largest?
5, therefore 5 is the Greatest Common Factor
Least Common Multiple (LCM)
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The smallest whole number that is a
multiple of two or more given numbers.
Reminder: A multiple is a product of a
counting number and another number.
Example:
The multiples of 3: 3, 6, 9, 12, 15, 18, 21, …
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LCM
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Find the LCM of 4 and 6
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4: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, …
6: 6, 12, 18, 24, 30, 36, 42, 48, 54, 60, …
What multiples do 4 and 6 have in
common?
12, 24, 36
Which is the least or smallest?
12
Your Turn
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Find the Greatest Common Factor of
12 and 15.
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12: 1, 2, 3, 4, 6, 12
15: 1, 3, 5, 15
The GCF of 12 and 15 is 3
Find the Least Common Multiple of
6 and 8.
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6: 6. 12, 18, 24, 30, …
8: 8, 16, 24, 32, 40, …
The LCM of 6 and 8 is 24