Personnummer is a ruby class that handles [Swedish personal identity number](http://en.wikipedia.org/wiki/Personal_identity_number_(Sweden\)).

$ gem install personnummer

>> p = Personnummer.new('830428-5912')
#>>Personnummer:0x007fc971369100 @valid=true, @control_digit=2, @divider="-", @serial=591, @born=#>>PersonnummerDate:0x007fc971368318 @divider="-", @day=28, @month=4, @year=1983> #<, @region="Skaraborgs län", @female=false> #<

>> p.valid?
=> true

Information about co-ordination numbers (in swedish)

These numbers are obtained by adding 60 to the day of the birth date

>> p = Personnummer.new('830488-5912')
=> #<Personnummer:0x007fbafd1458d8 @valid=false, @control_digit=2, @divider="-", @serial=591, @born=#<PersonnummerDate:0x007fbafd144af0 @divider="-", @day=88, @month=4, @year=1983>, @region="Skaraborgs län", @female=false>
>> p.born_at
=> #<Date: 1983-04-28 ((2445453j,0s,0n),+0s,2299161j)>
>> p.co_ordination_number?
=> true