$ ruby add_many_numbers.rb
["/Users/panayotismatsinopoulos/.rvm/rubies/ruby-2.2.3/lib/ruby/site_ruby/2.2.0", "/Users/panayotismatsinopoulos/.rvm/rubies/ruby-2.2.3/lib/ruby/site_ruby/2.2.0/x86_64-darwin14", "/Users/panayotismatsinopoulos/.rvm/rubies/ruby-2.2.3/lib/ruby/site_ruby", "/Users/panayotismatsinopoulos/.rvm/rubies/ruby-2.2.3/lib/ruby/vendor_ruby/2.2.0", "/Users/panayotismatsinopoulos/.rvm/rubies/ruby-2.2.3/lib/ruby/vendor_ruby/2.2.0/x86_64-darwin14", "/Users/panayotismatsinopoulos/.rvm/rubies/ruby-2.2.3/lib/ruby/vendor_ruby", "/Users/panayotismatsinopoulos/.rvm/rubies/ruby-2.2.3/lib/ruby/2.2.0", "/Users/panayotismatsinopoulos/.rvm/rubies/ruby-2.2.3/lib/ruby/2.2.0/x86_64-darwin14"]
/Users/panayotismatsinopoulos/.rvm/rubies/ruby-2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require': cannot load such file -- addition (LoadError)
        from /Users/panayotismatsinopoulos/.rvm/rubies/ruby-2.2.3/lib/ruby/site_ruby/2.2.0/rubygems/core_ext/kernel_require.rb:54:in `require'
        from add_many_numbers.rb:5:in `<main>'