Help with formula

[Guest]

I am working on a cash flow project for building a plant. I know the cost of
the various segments of the plant rounded to the nearest M. I need to show a
cash flow projection for each segment of the plant construction by month. I
am using a percent by month for the allocation for each different segment.
The monthly allocation is rounded to the nearest M also. The problem I am
having is that the monthly allocation for each segment does not always add up
to the total because of the rounding. How can I put in the last month
allocation formula a process that would, account for the difference between
the monthly allocation and the total being allocated, and then either add or
subtract that differnce to the last months allocated amount.

 

[Michael Malinsky]

If you have a simple spreadsheet with each month in a column then you could
accomplish this by manually entering the total for the year, calculating the
allocation for the first 11 months, then the final month would be the total
less the sum of the prior 11 months:

As a simple example, the months are in A1 through A12 and the total is in
A13. In A12 you would put:

=A13-SUM(A1:A11)