You can also create and use named ranges in the SUM function to quickly get the sum value. The above steps would give you the sum of the selected cells in the column. You can use the mouse or can use the arrow key (with arrow keys, hold the shift key and then use the arrow keys to select range of cells).
Pro Tip: You can also use the Autosum feature to get the sum of columns as well as rows. In the case of the empty cell (or text value), the auto-sum range would start below this cell.
One minor irritant when using Autosum is that it would not identify the correct range in case there are any empty cells in the range or any cell has the text value. If you select the cell which has the sum and look at the formula in it, you will notice that it refers to all the cells above it in the column. Note: Autosum automatically detects the range and includes all the cells in the SUM formula. As soon as you do this, it will give you the auto-sum in the cell below the selection. You can also use the Auto-sum by selecting the column that has the value and hitting the auto-sum option in the formula tab. The above steps would instantly give you the sum of the entire column in the selected cell.