You can't do this with format. While you can do it with a macro, you're
almost always better off to use another cell or column.

Put your multiplier in, say, A1, data in B1, then your formula is:
=$a$1*b1

Now your multiplier is easy to change without re-entering data, and errors
are easy to fix.

Regards,
Fred.

"Mikeebabe" wrote in message
...
I'm trying to format a cell in a way where the number I input will
automatically be multiplied by a number predetermined by me.
ie: I format cell a1 so it's contents is multiplied by .585
when I input the number 10 in cell a1 it will display as 5.85