Hi,
It's easier to help if you can be more specific.

What data is in the data table?
What cells and rows are involved?
Is the summary for all 158 accounts?
Will there ever be more than 158 accounts
What do you want the summary to look like?

I don't understand how the drop down relates to a summary.

Do you want to build the summary only for the accounts you choose in
the dropdown? If so, it seems that you'll need a command button to add
the accounts to the summary.

Dan