Attach a .PDF file to Excel

i have no idea of your actual path is
get the properties of doc by right clicking and use that
you do not use this by selecting hyperlink
just put
=HYPERLINK("\\Nasbox\Leaflets\Work Sheets\"&600&".PDF")
in the cell just as if you were putting =b1
i think you are linking to a shared drive so you need to link whatever the drive is
=HYPERLINK("g:\Nasbox\Leaflets\Work Sheets\"&600&".PDF")
yes you would have to change b1 but you could put a function in b1 to change it to what you need