1. Have Word Do the Math
If you need to total a column of figures in a table, Word can do the math. Once you've drawn the table, click in a cell in a column of numbers where you want the column total to appear. Go to Table Tools > Layout, and click Formula. If =SUM(ABOVE) does not automatically appear in the Formula dialog box’s Formula field, type it there. Select a format from the 'Number format' list and click OK. Word will automatically insert the total into the cell.
If you later change any of the values, click in the cell where the formula field code resides and press F9. You can also press Ctrl-A to select the entire document and press F9 to update all the field codes.