How to check for duplicate values within a column

[Andrew]

Hello all,
I am working on a spreadsheet and I need to figure out how to
define a unique string. In my sheet, column 1 is a list of classes
offered at a school. So column 1 contains strings. There are several
offerings of some classes and so the names of those classes show up
more than once in the name column. I am trying to count the number of
unique names of classes. So I need a way to filter out the doubles.
Assume that I have the following table. How can I determine how
many unique names are listed here?

Table 1.

Names Ages
---------------------
Joe 12
Sally 13
Jim 12
Joe 11
Bob 16
Alex 14
Andy 14
Jude 5
Alex 8


Thanks for the help.

Andrew

 

[Onkl]

Hello all,
I am working on a spreadsheet and I need to figure out how to
define a unique string. In my sheet, column 1 is a list of classes
offered at a school. So column 1 contains strings. There are several
offerings of some classes and so the names of those classes show up
more than once in the name column. I am trying to count the number of
unique names of classes. So I need a way to filter out the doubles.
Assume that I have the following table. How can I determine how
many unique names are listed here?

Table 1.

Names Ages
---------------------
Joe 12
Sally 13
Jim 12
Joe 11
Bob 16
Alex 14
Andy 14
Jude 5
Alex 8

Thanks for the help.

Andrew

I'll assume "Joe" is in A3:
In C4, type =IF(ISERROR(VLOOKUP(A4;A$3:A3;1;FALSE));"";"Double")
drag the formula down. On every second count of a double, collumn D
should say "Double".