1. Greatest Common Factor
Page 17 of INB

2. Greatest Common Factor (GCF)
Factors: numbers that are multiplied together.
Product: the answer to a multiplication problem
Factors are always in pairs, It must be multiplied by something.
1 is always a product, the number you are trying to find factors for is always its pair.

3. GCF RULES!! 1- Always a factor, paired with number looking for.
6- Both 2&3 must be factors.
7- Touchdown! (7,14,21,28,35,42,48,56,63,70)
2- Even: Ends in 0,2,4,6,8.
8- If 4 is a factor, check with division.
3- Sum of the two numbers must be divisible by 3.
9- Fingers
4- If even, check with division.
10- Ends in 0.
5- Must end in a 0 or 5.
11- Doubles.

4. HOMEWORK/CLASSWORK Find the GCF of 12 & 20 Find the GCF of 27 &45