Can someone explain to me how to find the GCF?
See below for an idea:
The GCF (Greatest Common Factor) can be found by first factoring down to primes of the numbers in question. Let's do this for the numbers 6, 9, and 15:
Now we find what is common to all the numbers.
The 6 has a 2 and a 3.
The 9 has two 3s
The 15 has a 3 and a 5.
The only number that is common to all of them is a single 3, and so that is the GCF.
If I wanted to find the GCF of those three numbers and also the number 4, we'd have:
Since the 4 doesn't have 3 as a factor, there is no factor that we've listed that is common to all four of them, and so the GCF is 1 (1 is a factor of all numbers).
- What is the GCF of 9 and 12?
List their prime factors:
#9= 3 xx3#
#12 =3 xx 2 xx 2#
Now highlight all of the terms that they have in common:
#9= color(red)3 xx3#
#12 =color(red)3 xx 2 xx 2#
They only share a
- What is the GCF of 12 and 18?
List their prime factors and highlight their common terms:
#12 = color(red)3 xx color(blue)2 xx 2#
#18 = color(red)3 xx 3 xx color(blue)2#
Since they have
#3 xx 2 = 6#
The GCF is
- What is the GCF of 9, 18, and 27?
List their prime factors and highlight the common terms:
#9 = color(red)3 xx color(blue)3#
#18 = color(red)3 xx color(blue)3 xx 2#
#27 = color(red)3 xx color(blue)3 xx 3#
Multiply these two terms together:
#3 xx 3 = 9#
The GCF is 9.