Tracks
/
Elixir
Elixir
/
Exercises
/
Prime Factors
Prime Factors

Prime Factors

Easy

Instructions

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!

Slow tests

One or several of the tests of this exercise have been tagged as :slow, because they might take a long time to finish. For this reason, they will not be run on the platform by the automated test runner. If you are solving this exercise directly on the platform in the web editor, you might want to consider downloading this exercise to your machine instead. This will allow you to run all the tests and check the efficiency of your solution.

Edit via GitHub The link opens in a new window or tab
Elixir Exercism

Ready to start Prime Factors?

Sign up to Exercism to learn and master Elixir with 57 concepts, 158 exercises, and real human mentoring, all for free.