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# Difference Of Squares

Find the difference between the square of the sum and the sum of the squares of the first N natural numbers.

The square of the sum of the first ten natural numbers is
(1 + 2 + ... + 10)² = 55² = 3025.

The sum of the squares of the first ten natural numbers is
1² + 2² + ... + 10² = 385.

Hence the difference between the square of the sum of the first
ten natural numbers and the sum of the squares of the first ten
natural numbers is 3025 - 385 = 2640.

## Running tests

In order to run the tests, issue the following command from the exercise
directory:

For running the tests provided, `rebar3` is used as it is the official build and
dependency management tool for erlang now. Please refer to [the tracks installation
instructions](http://exercism.io/languages/erlang/installation) on how to do that.

In order to run the tests, you can issue the following command from the exercise
directory.

```bash
$ rebar3 eunit
```

### Test versioning

Each problem defines a macro `TEST_VERSION` in the test file and
verifies that the solution defines and exports a function `test_version`
returning that same value.

To make tests pass, add the following to your solution:

```erlang
-export([test_version/0]).

test_version() ->
  1.
```

The benefit of this is that reviewers can see against which test version
an iteration was written if, for example, a previously posted solution
does not solve the current problem or passes current tests.

## Questions?

For detailed information about the Erlang track, please refer to the
[help page](http://exercism.io/languages/erlang) on the Exercism site.
This covers the basic information on setting up the development
environment expected by the exercises.

## Source

Problem 6 at Project Euler [http://projecteuler.net/problem=6](http://projecteuler.net/problem=6)

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

Version data entries

181 entries across 181 versions & 1 rubygems

Version Path
trackler-2.2.1.98 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.97 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.96 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.95 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.94 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.93 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.92 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.91 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.90 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.89 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.88 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.87 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.86 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.85 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.84 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.83 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.82 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.81 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.80 tracks/erlang/exercises/difference-of-squares/README.md
trackler-2.2.1.79 tracks/erlang/exercises/difference-of-squares/README.md