Way 2:  Factor Stacks

This method is a little more advanced and a lot more organized.  It doesn't really have an official name, but I call them "factor stacks."

Also, when numbers get big, it's easy to get lost and miss an easy factor...  So, we are going to be really systematic and work our way through our list of primes IN ORDER!

2, 3, 5, 7, 11, 13, ...
 

First, see if 2 works...  Keep trying it until it doesn't work anymore.

Then, try 3...  Keep trying it until it doesn't work anymore.

Then hit 5 until it doesn't work anymore.

Get it?

Those divisibility tests are really going to help!

This method is like a long division short-hand!

 

Find the prime factorization of  04-prime-factorizations-31.gif:


660 / 2 = 330  ...  2 goes in  ...  put the answer to 660 / 2 below

 

2 goes in again  ...  660 / 2 = 330 / 2 = 165