increment/random number problems

Hi Guys. Can anyone help me out???
Im looking to create a new ID number, in a cell, each time i open a template i have created. Ive managed to create a random number in a cell each time it opens, but, if i save the spreadsheet once data is entered and open it again, a new random number is created. Is it possible to create a random or incemented number only when the (blank) template is opened for the first time and remain there even when the file is opened and saved numerous times.

Thanks in advance.