siva kumar wrote:
> How to add "-" between the numbers
>  Eg:
> 123456789123456789 as 12-3456-7891-2345-6789
> 
> 
irb(main):001:0> str = "123456789123456789"
=> "123456789123456789"
irb(main):002:0> str.reverse.gsub(/..../, "\\0-").reverse
=> "12-3456-7891-2345-6789"

-- 
Alex