Factors

A factor is a number that can be divided evenly with 1 or more numbers.

12: 1, 12, 2, 6, 3, 4

1 x 12 = 12

2 x 6 = 12

3 x 4 = 12

The factors of 12 are 1, 12, 2, 6, 3, 4. Each pair of numbers multiplied together get 12. The way you do factors is take a number like 12. 1 abveously goes into 12 because 1 can go into any number above 0. Every number goes into itself. 1 x 12 = 12. Since 12 is an even number, 2 can go into it. But how many times? To figure it out, you go backwards. 12 divided by 2 is 6. 2 goes into 12 6 times. 2 x 6 = 12. You do the same thing to 3 and 4. It's easier if you start at 2 then work your way up.

Some tricks:

1. 2 if the number is even.
2. 3 if the sum of the digits are divisible by 3.
3. 5 if the number ends in 0 or 5.
4. 6 if the number is divisible by 2 and 3.
5. 9 if the sum of the digits are divisible by 9.
6. 10 if the number ends in o.
7. 11 (for 2 digit numbers) if the number is doubled.
8. 11 (for 3 digit numbers) if the two outside numbersadd up to the middle number.
   

When would you use factors? You use them when you have a party. How many candies go in each bag? I have 6 bags and 12 candies. 12 divided by 6 is 2. 2 and 6 are factors of 12. You would put 2 candies in each bag.

A great website for more practice is http://www.math.com/school/subject1/lessons/S1U3L1EX.html!!!!

Greatest Common Factor (GCF)

The Greatest Common Factor or GCF is the largest common factor of two or more numbers.

36: 1, 36, 2, 18, 3, 12, 4, 9, 6

48: 1, 48, 2, 24, 3, 16, 4, 12, 6, 8

The GCF would be 12 because 12 is the highest number they both have. The way you would do this is by listing the factors of each number. I look at the lowest number and it's factors. (36) Which ever factor is the highest number, I start there and work my way down. First, 36 can't go into 48. So, I move down to the next highest number. 18 can't go into 48 either. I go down again. 12 can go into 48. Maybe some of the lower numbers could go into it. But 12 is the highest one that can be divided by both numbers evenly. You would do the same with 3, 4, and maybe even 5 numbers. It's easier than you think.

Another website that would be good is http://www.helpwithfractions.com/greatest-common-factor.html!!!!

GOOD LUCK!!!!