# Grains

Calculate the number of grains of wheat on a chessboard given that the number
on each square doubles.

There once was a wise servant who saved the life of a prince. The king
promised to pay whatever the servant could dream up. Knowing that the
king loved chess, the servant told the king he would like to have grains
of wheat. One grain on the first square of a chess board. Two grains on
the next. Four on the third, and so on.

There are 64 squares on a chessboard.

Write code that shows:
- how many grains were on each square, and
- the total number of grains


## For bonus points

Did you get the tests passing and the code clean? If you want to, these
are some additional things you could try:

- Optimize for speed.
- Optimize for readability.

Then please share your thoughts in a comment on the submission. Did this
experiment make the code better? Worse? Did you learn anything from it?

## 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

JavaRanch Cattle Drive, exercise 6 [http://www.javaranch.com/grains.jsp](http://www.javaranch.com/grains.jsp)

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