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# Factorizing Large Numbers

In an earlier blog post, we talked about what prime factorization is and how to use a factor tree to factor numbers to their prime factors.

What if the number you are finding the prime factorization of is a larger number? The factor tree can become quite cumbersome.

## Using upside-down division

Another easy way of keeping track of the factorization is to do upside-down division.

Here’s how it works. Let’s start with a smaller number first – say 36.

You start by dividing 36 by 2.

36 divided by 2 is 18.

Then you divide 18 by 2.

18 divided by 2 is 9.

9 divided by 2 does not make a whole number, but divided by 3 it does.

9 divided by 3 is 3.

When completed, the prime factorization is the product of all the numbers around the outside.

2 x 2 x 3 x 3 = 36

## Factorizing Larger Numbers

Now, when you try the upside-down division with a larger number, you’ll see how easy this method is.

The answer is: 2 x 3 x 5 x 5 x 7 = 1050.