Cell formatting to show running result from given number

[Trp404]

I am attempting to developing an excel program to assist in analyzing, tracking and managing flight hours… I would be glad to email or attach what I have done so far if this would help.
I apologize for any confusion and will try to articulate what I need as close as I can, but I’m new at Excel.
Given:
12 columns (July-June) fiscal year.
31 rows (for each day of the month)
Row 32 shows total flight hours for each month.
Column 13 row 32 I want to show the sum of 300* (a constant) minus the total in column 13.
Example:
If the total hours in column 13 = 45 I would like the sum of -255 to show in column 13 row 32 reflecting that another 255 flight hours are required prior to June 31.
Thank you in advance for your expertise.
Trp404
* I require my pilots to fly 300 hours a year

 

[VoG]

That would cause a circular reference (M32 formula referencing M32).

maybe in M33

=300-M32

 

[Trp404]

Thank you so much.....ray:
using your formula with a column change it worked perfectly!
Trp 404