Download Finding the Greatest Common Factor The greatest common factor of

Finding the
Greatest
Common
Factor
The greatest
common factor
of two or more
numbers is the
greatest number
that is a factor of
every number.
There are two
methods for finding
the GCF.
1. Listing the factors
2. Using the Ladder
To find the GCF of two
numbers using a list, list the
factors of one number. Then
list the factors of the second
number. The GCF is the
greatest value that appears on
both lists.
1. Make a list to find the
GCF of 18 and 30
18: 1, 2, 3, 6, 9, 18
30: 1, 2, 3, 5, 6, 10, 15, 30
THE GCF of 18 and 30 is 6.
To find the GCF of two
numbers using the ladder
method, determine a prime
number that you can divide
evenly into each number.
Write the number on the side
and divide. Continue as far as
you can!
2. Use a ladder to find
the GCF of 27 and 36
3 27 36
3 9 12
3 4
3 x 3 =9
so the
GCF is 9