This gem is a wrapper to calculate the ISBN13 checksum.

Add this line to your application's Gemfile:

gem 'ISBN13'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install ISBN13

    require 'ISBN13'
  
    ISBN13.calculate('978019579915') # return 6
    ISBN13.complete('978019579915') # return '978019579916'

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/iogreggg/ISBN13.

The gem is available as open source under the terms of the MIT License.