Factors and GCF

Learing how to find factors is a pretty easy concept. A factor is a number that is divisible by another number. This means that a factor of any number will always be smaller than that number. In order to know the factors of any number, you will have to know the divisibility rules. Here they are-

2- If the number is even
3- If the sum of the digits is divisible by 3 ex.- 393... 3+9+3= 15 15 is divisible by three,
so so is 393.
4- If the last two digits are divisible by 4
5- If the last digit of the number ends in either 5 or 0
6- If the number is divisible by both 2 and 3
8- If the number formed by the last three digits is divisible by 8
9- If the sum of the digits is divisible by 9
10- If the number ends in a 0

Now that you the divisibility rules, I'll explain factors. You start with two, and go up to tean, finding if each number can be multiplied by anything to get the number. Here is an example:

The factors of 32 are:
1, 2, 4, 8, 16, 32

WORK:
32- 1, 32, 2, 16, 4, 8

NOTE:
1 is divisible by 32 because every number is divisible by itself and one (32 divided by1 is 32)

GCF:

When find a GCF, you have to be able to find factors. GCF stands for greatest common factor. That means, the highest factor that two or more numbers have in common. Here is an example of what to do:


Find the GCF of 25 and 30.

WORK: 25- 1, 25, 5
30- 1, 25, 2, 15, 3, 10, 5, 6

The GCF of 25 and 30 is 25, because out of the common factors, 25 is the biggest. This isn't the only way to do it, though. With more than two numbers, or with just two numbers, there is a shorter way. Here it is:

WORK: 25- 1, 25, 2, 15, 3, 10, 5, 6

Now, you would go down the list of factors, seeing if they are factors of 30 in your head. Then you would meantally figure out which one is the biggest/highest.

In real life, you might use this for making packages, or dividing things up. Hope you enjoyed my post!
Thanks for taking the time to read my post about factors
and GCFs. If you need more help, check out the
website below.


http://www.mathnstuff.com/math/spoken/here/1words/g/g3.htm