Download Chapter 1 Variables, Expressions, and Integers

4.2 Greatest Common Factor (
)
Math 7
Vocabulary
*** Common Factor: a whole number that is a
factor of 2 or more nonzero whole numbers.
***Greatest Common Factor (GCF): the greatest
of the common factors
***Relatively Prime: two or more nonzero whole
numbers whose GCF is 1.
Examples
** Ex. 1: Finding the Greatest Common Factor
3 methods
Strategy 1: To find the GCF, list all the factors of
each number. The largest factor that is in
both numbers is the GCF.
Strategy 2: To find the GCF, write the prime
factorization of each number and identify which
factors are in each number.
Strategy 3: Upside down division:
2 /60 96
2 /30 48
3 /15 24
5 8
Try these on your own: Find the GCF using any
method
1.
16, 28
2.
15, 75, 20
3. What is the greatest number of ensembles that
can be formed with 32 violinists, 40 violists, and 16
cellists? How many of each instrument will be in
each ensemble?
** Ex. 2: Identifying Relatively Prime Numbers
Try these on your own: Tell whether the numbers are
relatively prime.
1.
13, 24
2.
16, 25
Guided Practice/Ticket out the Door