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# 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!
* * * *
For installation and learning resources, refer to the
[exercism help page](http://exercism.io/languages/ruby).
For running the tests provided, you will need the Minitest gem. Open a
terminal window and run the following command to install minitest:
gem install minitest
If you would like color output, you can `require 'minitest/pride'` in
the test file, or note the alternative instruction, below, for running
the test file.
In order to run the test, you can run the test file from the exercise
directory. For example, if the test suite is called
`hello_world_test.rb`, you can run the following command:
ruby hello_world_test.rb
To include color from the command line:
ruby -r minitest/pride hello_world_test.rb
## 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.
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102 entries across 102 versions & 1 rubygems