» Summing values in vertical and horizontal ranges in Microsoft Excel

Select the range of data, including the empty rows and columns surrounding the data A1:K11 (see screenshot).
A quick technique for selecting data without using the mouse:
select cell A1, press Shift, and select cell K11.
Now press Alt+= or click the AutoSum icon.

Result: The SUM formula is added to the end of each row and the bottom of each column.