You have 256 columns in your worksheet.
A helper column is one of those empty columns that isn't being used. You'll use
it to "help" you accomplish something.
In this case, you'll use it to extract the last two digits and then use it for
the key for your sort.
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In general, I like to have my helper columns near the original data. I'll
insert a column just to the right (or left) of the original data.
If I need to be able to do this thing over and over, I'll leave the column
there. (and if it's not pretty enough, I'll hide that column.)
If I only have to do this thing once, I'll do my stuff and then delete that
helper column.