When you suspect that a column does not have a consistent formula used throughout, the following GO TO Special feature will help.
1. Select the cells with formulas in the column that you are questioning
2. Press F5 or Ctrl + G then Special
3. Select Column differences
4. Click OK
5. All cells that differ from the active cell in the selected column will be selected. There is always one active cell in a selection, whether this is a range, row, or column. By pressing ENTER or TAB, you can change the location of the active cell, which by default is the first cell in a column.
NOTE: If more than one column is selected, the comparison is performed for each column of that selection. The cell that is used in the comparison for each additional column is located in the same row as the active cell.
Below, the cell with an inconsistent formula is marked: