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Today I learned an easy way to do prime factors from my son. We were working on his homework. We’ll build a prime factor tree to accomplish this. I know a lot of you already know this stuff, but I don’t think I learned it in school, and if I did. I have forgotten it.

In case you don’t know what a prime number is, it’s a number that can’t be divided into any other number and get a 0 remainder.

I believe prime numbers up to 13 are.
0, 1, 2, 3, 5, 7, 9, 11, 13

However we aren’t going to use the first 2 because 0 and 1 can be divided into anything. We’re trying to find the primes from 2 to 13.

Pick a number any number any number.

  80
 /  \
8   10

8×10 = 80

     80
    /  \
   8    \
  / \    \
[2]   4   \
          10

2 x 4 = 8
We’ve found our first prime which is 2.

     80
    /  \
   8    \
  / \    \
[2]   4   \
     / \   \
   [2] [2] 10

We’ve now found our next prime numbers because 2 x 2 = 4
So far our lowest prime numbers are 2 x 2 x 2 = 8

     80
    /  \
   8    \
  / \    \
[2]   4   \
     / \   \
   [2] [2] 10
          /  \
        [2]  [5]

We have now found our last 2 prime numbers 2 and 5.

So in the end our prime factorization is: 2 x 2 x 2 x 2 x 5 = 80

I’m so glad my son is teaching me math. This is fun stuff.