You can make that cell look empty with a formula like:
=if(c3="","",40-C3-0.2)

Or you could even add a little validity check:
=if(isnumber(c3),40-C3-0.2,"")

Sammy wrote:

Hello, I'm new to excel, I'm trying a simple formula (=40-C3-0.2)
& I'm wondering if it is possible to hide the result of my formula until I
had added an amount into cell C3, as it results in showing 39.8 until imput
another number into C3,
I would like the result to remain blank until I put a number in C3.

Thanks for any help.

--

Dave Peterson