Two ways:

=IF(M3="","",L25-M3)

or

=IF(M3="","",TODAY()-M3)

HTH,
Paul

--

"Terry Rogers" wrote in message
...
I've entered the formula =(L25-M3) in a target cell to count the length of
stay of patients on a hospital unit. L 25 contains the formula to enter
the
current date,that is =today(). Each cell in column "M" is the hand
entered
admission date. This formula works but I need it to ONLY do the
calculation
if there is a value entered in column "M." What argument do I add to
suppress the calculation if "M" is blank? Currently it displays a bizzar
number.