Add data in multiple columns (dynamic # of columns)

Hi all,

I'm creating a budget spreadsheet that is going to have multiple months in it (in a single sheet). Each month has four columns, and one of those columns is "Amount budgeted". Now, as I add extra months to the excel sheet, this column starts repeating (per month). To get some calculations going, my current goal is to add the value in each "Amount Budgeted" column that repeats for every month.

In other words, I have a 100 rows, with interesting data in columns 10, 14, 18, 22, 26 and so on. If the current column that I'm working in is Column 30, is there an easy way/formula to find the sum of past columns?

Hope this makes sense!

Thanks

Thanks Glenn! I updated the example slightly, as I realized my example wasn't perfect.

I offset it a little bit to make the example clearer, but B8-B10 will have another month underneath as well.