In IRB you can retrieve the last return value from a command by using the underscore
$ irb >> 2*3 => 6 >> _ + 7 => 13 >> _ => 13
This also works in the Rails console:
$ script/console >> User.first => #<User id: 7, first_name ... >> user = _ => #<User id: 7, first_name ... >> user => #<User id: 7, first_name ...
This is quite useful, when you forgot to assign the return value of an expression to a variable.
You can use HTML tags for formatting. Wrap code in <code> tags and multiple lines of code in <pre><code> tags.