Excel - combine multiple columns to a single column

Question

My excel sheet looks like this

      c1        c2      c3      c4

ROW1   abc      def      1       2

ROW2   abc      def      3       4

ROW3   klm      e         


        

Answer 1

You can do this using the excel concatenate function. Here's a link to a good tutorial

Also, to deal with the duplicates, you can have excel highlight duplicate entries so they can be easily deleted. See here