select cells
Select a cell: Click it.
Select a range of cells: Click a cell, then drag a white dot any direction across the range of cells.
If you drag the yellow dot, you copy the cell contents to the rows you drag over. If you do this accidentally, drag the yellow dot back to its original position or press Command-Z on the keyboard to undo the action.
Select similar cells in a pivot table: Click a cell, Control-click, then choose Select Similar Cells. For example, you can select one Total row cell, then choose Select Similar Cells to select them all.