# Prime Factors

Compute the prime factors of a given natural number.

A prime number is only evenly divisible by itself and 1.

Note that 1 is not a prime number.

## Example

What are the prime factors of 60?

- Our first divisor is 2. 2 goes into 60, leaving 30.
- 2 goes into 30, leaving 15.
  - 2 doesn't go cleanly into 15. So let's move on to our next divisor, 3.
- 3 goes cleanly into 15, leaving 5.
  - 3 does not go cleanly into 5. The next possible factor is 4.
  - 4 does not go cleanly into 5. The next possible factor is 5.
- 5 does go cleanly into 5.
- We're left only with 1, so now, we're done.

Our successful divisors in that computation represent the list of prime
factors of 60: 2, 2, 3, and 5.

You can check this yourself:

- 2 * 2 * 3 * 5
- = 4 * 15
- = 60
- Success!

## Getting Started

Make sure you have read the
[C page](http://exercism.io/languages/c) on the Exercism site. This covers
the basic information on setting up the development environment expected
by the exercises.


## Passing the Tests

Get the first test compiling, linking and passing by following the [three
rules of test-driven development][3-tdd-rules].

The included makefile can be used to create and run the tests using the `test`
task.

    make test

Create just the functions you need to satisfy any compiler errors and get the
test to fail. Then write just enough code to get the test to pass. Once you've
done that, move onto the next test.

[3-tdd-rules]: http://butunclebob.com/ArticleS.UncleBob.TheThreeRulesOfTdd

As you progress through the tests, take the time to refactor your
implementation for readability and expressiveness and then go on to the next
test.

Try to use standard C99 facilities in preference to writing your own
low-level algorithms or facilities by hand.

## Source

The Prime Factors Kata by Uncle Bob [http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata](http://butunclebob.com/ArticleS.UncleBob.ThePrimeFactorsKata)

## Submitting Incomplete Solutions
It's possible to submit an incomplete solution so you can see how others have completed the exercise.