I need help with a spreadsheet that is used to calculate a companies
forecast. How this works is during a month a spreadsheet calculates the
hours worked to get a financial forecast.We put on there planned weeks hours
and than fill in at the end of the week the actual hours.

This is a spreadsheet where you add the actual columns (these are the weeks
that have happened) that occurred with the forecasted columns. (These are
the columns that have not occurred.

(Example)
If the 1a is filled and is the only (a) column filled than you calculate the
1a+2+3+4 columns
If the 1a and the 2a is filled than you calculate the 1a+2a+3+4 columns
If the 1a and the 2a and the 3a is filled than you calculate the 1a+2a+3a+4
columns


Attempted with no success below. I tried to work backwards to see what week
we were in and than calculate accordingly.
----------------------------------------------------------------
Column 1, 1a, 2, 2a, 3, 3a, 4, 4a

If column 4a 0 than add column 4a+3a+2a+1a

else add column 1a+2a+3a+4