Applying unique ID's to rows but keep same unique ID number for duplicates

[sirjames2829]

I'm using Excel 2002 and I'm a beginner.
I have three columns labled from Columns A - C as: LastName, FirstName, and PostedUnits.
I need to do three things. The first is too assign an Unique ID to the rows but I need to make sure that for the duplicate LastName's to have the same Unique ID.
The Second thing I need to do is to total up the PostedUnits for each duplicate LastName.
Once I get the total of PostedUnits for each LastName, I want to delete the duplicates LastName's and and my finished report is to just have the LastName, FirstName, and TotalPostedUnits and no duplicates.

I'm assuming I need to create a new column in A and name it UniqueID? Then create another column after PostedUnits and name it TotalPostedUnits, Correct?

Then, I will need help with the formulas and any other steps to complete this please.

Thank you.

[matt.nicolai]

What is the purpose of the Unique ID? I would recommend using a Pivot Table with LastName in Row Labels and PostedUnits in Values.

[sirjames2829]

Like I mentioned, I'm just a beginner.