Don't do it that way. It can be done, but you can be sure you'll get yourself into trouble some time.
Use an extra cell (which you can hide) with a formula like

=IF(A1="H",-1,"YesWhatElse")

YesWhatElse: you didn't specify

--
Kind regards,

Niek Otten

"Guybon Berry" <Guybon wrote in message
...
I am completely confused.
H represents a staff member on Holiday.
I have a total number of staff and want H to represent -1.
If H is entered in any of the range of cells selected it must represent -1
and be able to be included in a formula.
Please help.