if my assumption was correct (although I don't know why it has the .55 on the end) and your time value of 906,151,655.55 = 06/15/2009 16:58:05 then the formula of
dateadd("s",-906151655.55,#06/15/2009 16:58:05#)
returns a value of #09-27-1980 8:10:30PM# indicating your formula should be:
dateadd("s",{table.numberfield},#09/27/1980 08:10:30PM#)
Again, I am guessing at that initial concept of it being a count of seconds and "09/27/1980 08:10:30PM" does seem to be rather arbitrary begin point...
Edited by DBlank - 19 Jun 2009 at 12:09pm