How do I get the Fortnight number of the year from a date?

[Daz]

I want to get the fortnight number of the year into a cell, i.e 1-1-2009 will
be fortnight number one and 15-1-2009 will be fortnight number 2.

As well as the date I also have the day number of the year

 

[Mike H]

Maybe this,

=ROUNDUP((A1-DATE(YEAR(A1),1,0))/14,0)

Mike