http://www.exceltip.com/exceltips.php?view=toptips
http://j-walk.com/ss/excel/usertips/formulatips.htm

To count only the number of unique entries in a specified range:

The range can be all in one column or row, or may span multiple (adjoining) columns/rows.
The formula would be written as: =SUMPRODUCT((1/COUNTIF(A1:C5,A1:C5&"")))
where A1:C5 is replaced with the range you want to apply the count to.


To separate first name and last names:

1. Select Column A or the range of cells containing the list of names.
2. From the Data menu, select Text to Columns.
3. In Step 1 of 3, select Delimited.
4. In Step 2 of 3, select the Space checkbox.
5. In Step 3 of 3, in the Destination box, select cell B1, and then click Finish.


Select Region:

1. choose a cell A1
2. type C10 in the name box
3. press shift-enter


Split number/string into digits/char:

=MID($A2,COLUMN()-1,1)


Remove Duplicates:
=IF(COUNTIF(A$2:A2,A2)>1,"",A2)