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How to Concatenate multiple columns of numbers?
I am using Excel 2007 VBA -- and need to concatenate 100 columns
of numbers into 50, with 2137 rows. If a cell is empty, then do
not concatenate. End script when first empty row is reached.
Two columns of numbers will be concatenated and separated by
an underscore.

Numbers in each cell come from database, and will appear
to be random to the casual observer, though each number has
significant meaning.

Example:

Columns
A1----B1----C1----D1----E1----F1
12----2----13----1----256----3

After VBA script is run:

Columns
A1------B1------C1
12_2----13_1----256_3