The largest number that is a factor or divisor or both of A & B
There are three methods:
- List the Factors
- Prime Factorization
- Linear (Cuisenaire rods)
- List the Factor
To get the GCF you list every multiple that would equal the two numbers
So we will find the GCF of (3,4)
Then circle every number that the two have in common
The GCF is the biggest number that they both have in common
Prime Factorization
Make a factor tree and get prime factors
(in this example we will be using 75 and 60)
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| Image Source Page: http://misterwhalen.blogspot.com/2008/10/factor-trees.html |
Next you find all the prime factors you can then make a venn diagram and use the prime numbers to find the common numbers
3x5=15
GCF(75,60) is 15
Linear (Cuisenaire Rods)
Each color has a certain number
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| Image Source Page: http://www.cet.ac.il/math-international/addition1.htm |
Find the GCF of (6,12)
whichever color rods can be used in both the least amount of times is the GCF of the two numbers
A cute little song about GCF & LCM
A fun little game
