Here's what I'm trying to do with so far no success:

I have a matrix where numbers are the column headers and letters are
the row headers. I want to take a sum of the cells that meet both
column header and row header criteria. For example, the column
headers could be any number between 1 and 10 (not necessarily in any
order, there may be more than one of any number). The row headers
could be any letter between A and M (not necessarily in any order,
there could be more than 1 of any letter). I want to know the sum of
all the cells that are in a "2" column as well as a "B" row.

Or, the sum of those cells that are in a "2" column and are in rows
5:20.

Ideas?