summing data when number of columns is variable

[michaelpaul]

Although this seems easy, i can't figure out how to do it short of writing a macro.

All i want to do is enter data into a table. For my case, i have 52 week projections so I have a value for each week. I then just want to enter the number of weeks to add in a seperate cell and then simply have a column that adds all of my data for the specified number of weeks. that way, if I want to look at 5 week projections instead of 3 week projections, everything is automatically updated.

I know I could write a macro, pass the array to the macro and simly use a count and running sum command but I'd like to do it all on in the native spreadsheet rather than work in the macro environment.

any help would be appreciated

thanks.

 

[jaya]

Enter the following formula in the top row (row 1 in this instance) and copy it down.

=SUM(A1:INDEX($A$1:$J$18,ROW(),L$22))

A1:J18 is the data range. L22 is the cell where you enter the no. of weeks to add.