1) Under Tools Options, select the Settings tab and uncheck the 'R1C1
reference style'.
2) In the first row where you want the totals, enter a formula, something
like =a2+c2+e2 or =sum(a2:f2), whichever more easily specifies the columns
you want added. Autofill that formula into subsequent rows.

"Measurement Consultant" wrote:

The column headers are displaying numbers (1,2,3) instead of letters (A,B,C),
which is making it difficult for me to type in formulas. Ultimately, I'd
like to have a column at the right end of my spreadsheet that totals a
specific set of columns *within each row*. How do I do this?

I am using Excel that came with Microsoft Windows XP